diff --git a/api/current.txt b/api/current.txt
index 21c2999..30d04a4 100644
--- a/api/current.txt
+++ b/api/current.txt
@@ -22825,24 +22825,6 @@
     method @Deprecated public boolean usedInFix();
   }
 
-  @Deprecated public final class GpsStatus {
-    method @Deprecated public int getMaxSatellites();
-    method @Deprecated public Iterable<android.location.GpsSatellite> getSatellites();
-    method @Deprecated public int getTimeToFirstFix();
-    field @Deprecated public static final int GPS_EVENT_FIRST_FIX = 3; // 0x3
-    field @Deprecated public static final int GPS_EVENT_SATELLITE_STATUS = 4; // 0x4
-    field @Deprecated public static final int GPS_EVENT_STARTED = 1; // 0x1
-    field @Deprecated public static final int GPS_EVENT_STOPPED = 2; // 0x2
-  }
-
-  @Deprecated public static interface GpsStatus.Listener {
-    method @Deprecated public void onGpsStatusChanged(int);
-  }
-
-  @Deprecated public static interface GpsStatus.NmeaListener {
-    method @Deprecated public void onNmeaReceived(long, String);
-  }
-
   public class Location implements android.os.Parcelable {
     ctor public Location(String);
     ctor public Location(android.location.Location);
@@ -22911,55 +22893,50 @@
   }
 
   public class LocationManager {
-    method @Deprecated @RequiresPermission(android.Manifest.permission.ACCESS_FINE_LOCATION) public boolean addGpsStatusListener(android.location.GpsStatus.Listener);
-    method @Deprecated @RequiresPermission(android.Manifest.permission.ACCESS_FINE_LOCATION) public boolean addNmeaListener(android.location.GpsStatus.NmeaListener);
-    method @RequiresPermission(android.Manifest.permission.ACCESS_FINE_LOCATION) public boolean addNmeaListener(android.location.OnNmeaMessageListener);
-    method @RequiresPermission(android.Manifest.permission.ACCESS_FINE_LOCATION) public boolean addNmeaListener(android.location.OnNmeaMessageListener, android.os.Handler);
-    method @RequiresPermission(anyOf={android.Manifest.permission.ACCESS_COARSE_LOCATION, android.Manifest.permission.ACCESS_FINE_LOCATION}) public void addProximityAlert(double, double, float, long, android.app.PendingIntent);
-    method public void addTestProvider(String, boolean, boolean, boolean, boolean, boolean, boolean, boolean, int, int);
-    method @Deprecated public void clearTestProviderEnabled(String);
-    method @Deprecated public void clearTestProviderLocation(String);
-    method @Deprecated public void clearTestProviderStatus(String);
-    method public java.util.List<java.lang.String> getAllProviders();
-    method public String getBestProvider(android.location.Criteria, boolean);
+    method @RequiresPermission(android.Manifest.permission.ACCESS_FINE_LOCATION) public boolean addNmeaListener(@NonNull android.location.OnNmeaMessageListener);
+    method @RequiresPermission(android.Manifest.permission.ACCESS_FINE_LOCATION) public boolean addNmeaListener(@NonNull android.location.OnNmeaMessageListener, @Nullable android.os.Handler);
+    method @RequiresPermission(anyOf={android.Manifest.permission.ACCESS_COARSE_LOCATION, android.Manifest.permission.ACCESS_FINE_LOCATION}) public void addProximityAlert(double, double, float, long, @NonNull android.app.PendingIntent);
+    method public void addTestProvider(@NonNull String, boolean, boolean, boolean, boolean, boolean, boolean, boolean, int, int);
+    method @Deprecated public void clearTestProviderEnabled(@NonNull String);
+    method @Deprecated public void clearTestProviderLocation(@NonNull String);
+    method @Deprecated public void clearTestProviderStatus(@NonNull String);
+    method @NonNull public java.util.List<java.lang.String> getAllProviders();
+    method @Nullable public String getBestProvider(@NonNull android.location.Criteria, boolean);
     method @Nullable public String getGnssHardwareModelName();
     method public int getGnssYearOfHardware();
-    method @Deprecated @RequiresPermission(android.Manifest.permission.ACCESS_FINE_LOCATION) public android.location.GpsStatus getGpsStatus(android.location.GpsStatus);
-    method @RequiresPermission(anyOf={android.Manifest.permission.ACCESS_COARSE_LOCATION, android.Manifest.permission.ACCESS_FINE_LOCATION}) public android.location.Location getLastKnownLocation(String);
-    method public android.location.LocationProvider getProvider(String);
-    method public java.util.List<java.lang.String> getProviders(boolean);
-    method public java.util.List<java.lang.String> getProviders(android.location.Criteria, boolean);
+    method @RequiresPermission(anyOf={android.Manifest.permission.ACCESS_COARSE_LOCATION, android.Manifest.permission.ACCESS_FINE_LOCATION}) @Nullable public android.location.Location getLastKnownLocation(@NonNull String);
+    method @Nullable public android.location.LocationProvider getProvider(@NonNull String);
+    method @NonNull public java.util.List<java.lang.String> getProviders(boolean);
+    method @NonNull public java.util.List<java.lang.String> getProviders(@NonNull android.location.Criteria, boolean);
     method public boolean isLocationEnabled();
-    method public boolean isProviderEnabled(String);
-    method @RequiresPermission(android.Manifest.permission.ACCESS_FINE_LOCATION) public boolean registerGnssMeasurementsCallback(android.location.GnssMeasurementsEvent.Callback);
-    method @RequiresPermission(android.Manifest.permission.ACCESS_FINE_LOCATION) public boolean registerGnssMeasurementsCallback(android.location.GnssMeasurementsEvent.Callback, android.os.Handler);
-    method public boolean registerGnssNavigationMessageCallback(android.location.GnssNavigationMessage.Callback);
-    method @RequiresPermission(android.Manifest.permission.ACCESS_FINE_LOCATION) public boolean registerGnssNavigationMessageCallback(android.location.GnssNavigationMessage.Callback, android.os.Handler);
-    method @RequiresPermission(android.Manifest.permission.ACCESS_FINE_LOCATION) public boolean registerGnssStatusCallback(android.location.GnssStatus.Callback);
-    method @RequiresPermission(android.Manifest.permission.ACCESS_FINE_LOCATION) public boolean registerGnssStatusCallback(android.location.GnssStatus.Callback, android.os.Handler);
-    method @Deprecated public void removeGpsStatusListener(android.location.GpsStatus.Listener);
-    method @Deprecated public void removeNmeaListener(android.location.GpsStatus.NmeaListener);
-    method public void removeNmeaListener(android.location.OnNmeaMessageListener);
-    method @RequiresPermission(anyOf={"android.permission.ACCESS_COARSE_LOCATION", "android.permission.ACCESS_FINE_LOCATION"}, apis="..22") public void removeProximityAlert(android.app.PendingIntent);
-    method public void removeTestProvider(String);
-    method @RequiresPermission(anyOf={"android.permission.ACCESS_COARSE_LOCATION", "android.permission.ACCESS_FINE_LOCATION"}, apis="..22") public void removeUpdates(android.location.LocationListener);
-    method public void removeUpdates(android.app.PendingIntent);
-    method @RequiresPermission(anyOf={android.Manifest.permission.ACCESS_COARSE_LOCATION, android.Manifest.permission.ACCESS_FINE_LOCATION}) public void requestLocationUpdates(String, long, float, android.location.LocationListener);
-    method @RequiresPermission(anyOf={android.Manifest.permission.ACCESS_COARSE_LOCATION, android.Manifest.permission.ACCESS_FINE_LOCATION}) public void requestLocationUpdates(String, long, float, android.location.LocationListener, android.os.Looper);
-    method @RequiresPermission(anyOf={android.Manifest.permission.ACCESS_COARSE_LOCATION, android.Manifest.permission.ACCESS_FINE_LOCATION}) public void requestLocationUpdates(long, float, android.location.Criteria, android.location.LocationListener, android.os.Looper);
-    method @RequiresPermission(anyOf={android.Manifest.permission.ACCESS_COARSE_LOCATION, android.Manifest.permission.ACCESS_FINE_LOCATION}) public void requestLocationUpdates(String, long, float, android.app.PendingIntent);
-    method @RequiresPermission(anyOf={android.Manifest.permission.ACCESS_COARSE_LOCATION, android.Manifest.permission.ACCESS_FINE_LOCATION}) public void requestLocationUpdates(long, float, android.location.Criteria, android.app.PendingIntent);
-    method @RequiresPermission(anyOf={android.Manifest.permission.ACCESS_COARSE_LOCATION, android.Manifest.permission.ACCESS_FINE_LOCATION}) public void requestSingleUpdate(String, android.location.LocationListener, android.os.Looper);
-    method @RequiresPermission(anyOf={android.Manifest.permission.ACCESS_COARSE_LOCATION, android.Manifest.permission.ACCESS_FINE_LOCATION}) public void requestSingleUpdate(android.location.Criteria, android.location.LocationListener, android.os.Looper);
-    method @RequiresPermission(anyOf={android.Manifest.permission.ACCESS_COARSE_LOCATION, android.Manifest.permission.ACCESS_FINE_LOCATION}) public void requestSingleUpdate(String, android.app.PendingIntent);
-    method @RequiresPermission(anyOf={android.Manifest.permission.ACCESS_COARSE_LOCATION, android.Manifest.permission.ACCESS_FINE_LOCATION}) public void requestSingleUpdate(android.location.Criteria, android.app.PendingIntent);
-    method public boolean sendExtraCommand(String, String, android.os.Bundle);
-    method public void setTestProviderEnabled(String, boolean);
-    method public void setTestProviderLocation(String, android.location.Location);
-    method @Deprecated public void setTestProviderStatus(String, int, android.os.Bundle, long);
-    method public void unregisterGnssMeasurementsCallback(android.location.GnssMeasurementsEvent.Callback);
-    method public void unregisterGnssNavigationMessageCallback(android.location.GnssNavigationMessage.Callback);
-    method public void unregisterGnssStatusCallback(android.location.GnssStatus.Callback);
+    method public boolean isProviderEnabled(@NonNull String);
+    method @RequiresPermission(android.Manifest.permission.ACCESS_FINE_LOCATION) public boolean registerGnssMeasurementsCallback(@NonNull android.location.GnssMeasurementsEvent.Callback);
+    method @RequiresPermission(android.Manifest.permission.ACCESS_FINE_LOCATION) public boolean registerGnssMeasurementsCallback(@NonNull android.location.GnssMeasurementsEvent.Callback, @Nullable android.os.Handler);
+    method public boolean registerGnssNavigationMessageCallback(@NonNull android.location.GnssNavigationMessage.Callback);
+    method @RequiresPermission(android.Manifest.permission.ACCESS_FINE_LOCATION) public boolean registerGnssNavigationMessageCallback(@NonNull android.location.GnssNavigationMessage.Callback, @Nullable android.os.Handler);
+    method @RequiresPermission(android.Manifest.permission.ACCESS_FINE_LOCATION) public boolean registerGnssStatusCallback(@NonNull android.location.GnssStatus.Callback);
+    method @RequiresPermission(android.Manifest.permission.ACCESS_FINE_LOCATION) public boolean registerGnssStatusCallback(@NonNull android.location.GnssStatus.Callback, @Nullable android.os.Handler);
+    method public void removeNmeaListener(@NonNull android.location.OnNmeaMessageListener);
+    method @RequiresPermission(anyOf={"android.permission.ACCESS_COARSE_LOCATION", "android.permission.ACCESS_FINE_LOCATION"}, apis="..22") public void removeProximityAlert(@NonNull android.app.PendingIntent);
+    method public void removeTestProvider(@NonNull String);
+    method @RequiresPermission(anyOf={"android.permission.ACCESS_COARSE_LOCATION", "android.permission.ACCESS_FINE_LOCATION"}, apis="..22") public void removeUpdates(@NonNull android.location.LocationListener);
+    method public void removeUpdates(@NonNull android.app.PendingIntent);
+    method @RequiresPermission(anyOf={android.Manifest.permission.ACCESS_COARSE_LOCATION, android.Manifest.permission.ACCESS_FINE_LOCATION}) public void requestLocationUpdates(@NonNull String, long, float, @NonNull android.location.LocationListener);
+    method @RequiresPermission(anyOf={android.Manifest.permission.ACCESS_COARSE_LOCATION, android.Manifest.permission.ACCESS_FINE_LOCATION}) public void requestLocationUpdates(@NonNull String, long, float, @NonNull android.location.LocationListener, @Nullable android.os.Looper);
+    method @RequiresPermission(anyOf={android.Manifest.permission.ACCESS_COARSE_LOCATION, android.Manifest.permission.ACCESS_FINE_LOCATION}) public void requestLocationUpdates(long, float, @NonNull android.location.Criteria, @NonNull android.location.LocationListener, @Nullable android.os.Looper);
+    method @RequiresPermission(anyOf={android.Manifest.permission.ACCESS_COARSE_LOCATION, android.Manifest.permission.ACCESS_FINE_LOCATION}) public void requestLocationUpdates(@NonNull String, long, float, @NonNull android.app.PendingIntent);
+    method @RequiresPermission(anyOf={android.Manifest.permission.ACCESS_COARSE_LOCATION, android.Manifest.permission.ACCESS_FINE_LOCATION}) public void requestLocationUpdates(long, float, @NonNull android.location.Criteria, @NonNull android.app.PendingIntent);
+    method @RequiresPermission(anyOf={android.Manifest.permission.ACCESS_COARSE_LOCATION, android.Manifest.permission.ACCESS_FINE_LOCATION}) public void requestSingleUpdate(@NonNull String, @NonNull android.location.LocationListener, @Nullable android.os.Looper);
+    method @RequiresPermission(anyOf={android.Manifest.permission.ACCESS_COARSE_LOCATION, android.Manifest.permission.ACCESS_FINE_LOCATION}) public void requestSingleUpdate(@NonNull android.location.Criteria, @NonNull android.location.LocationListener, @Nullable android.os.Looper);
+    method @RequiresPermission(anyOf={android.Manifest.permission.ACCESS_COARSE_LOCATION, android.Manifest.permission.ACCESS_FINE_LOCATION}) public void requestSingleUpdate(@NonNull String, @NonNull android.app.PendingIntent);
+    method @RequiresPermission(anyOf={android.Manifest.permission.ACCESS_COARSE_LOCATION, android.Manifest.permission.ACCESS_FINE_LOCATION}) public void requestSingleUpdate(@NonNull android.location.Criteria, @NonNull android.app.PendingIntent);
+    method public boolean sendExtraCommand(@NonNull String, @NonNull String, @Nullable android.os.Bundle);
+    method public void setTestProviderEnabled(@NonNull String, boolean);
+    method public void setTestProviderLocation(@NonNull String, @NonNull android.location.Location);
+    method @Deprecated public void setTestProviderStatus(@NonNull String, int, @Nullable android.os.Bundle, long);
+    method public void unregisterGnssMeasurementsCallback(@NonNull android.location.GnssMeasurementsEvent.Callback);
+    method public void unregisterGnssNavigationMessageCallback(@NonNull android.location.GnssNavigationMessage.Callback);
+    method public void unregisterGnssStatusCallback(@NonNull android.location.GnssStatus.Callback);
     field public static final String GPS_PROVIDER = "gps";
     field public static final String KEY_LOCATION_CHANGED = "location";
     field public static final String KEY_PROVIDER_ENABLED = "providerEnabled";
diff --git a/api/removed.txt b/api/removed.txt
index fdfaf91..7a06803 100644
--- a/api/removed.txt
+++ b/api/removed.txt
@@ -282,12 +282,38 @@
 
 package android.location {
 
+  @Deprecated public final class GpsStatus {
+    method public int getMaxSatellites();
+    method public Iterable<android.location.GpsSatellite> getSatellites();
+    method public int getTimeToFirstFix();
+    field public static final int GPS_EVENT_FIRST_FIX = 3; // 0x3
+    field public static final int GPS_EVENT_SATELLITE_STATUS = 4; // 0x4
+    field public static final int GPS_EVENT_STARTED = 1; // 0x1
+    field public static final int GPS_EVENT_STOPPED = 2; // 0x2
+  }
+
+  @Deprecated public static interface GpsStatus.Listener {
+    method public void onGpsStatusChanged(int);
+  }
+
+  @Deprecated public static interface GpsStatus.NmeaListener {
+    method public void onNmeaReceived(long, String);
+  }
+
   public class Location implements android.os.Parcelable {
     method @Deprecated public void removeBearingAccuracy();
     method @Deprecated public void removeSpeedAccuracy();
     method @Deprecated public void removeVerticalAccuracy();
   }
 
+  public class LocationManager {
+    method @Deprecated @RequiresPermission(android.Manifest.permission.ACCESS_FINE_LOCATION) public boolean addGpsStatusListener(android.location.GpsStatus.Listener);
+    method @Deprecated @RequiresPermission(android.Manifest.permission.ACCESS_FINE_LOCATION) public boolean addNmeaListener(android.location.GpsStatus.NmeaListener);
+    method @Deprecated @Nullable @RequiresPermission(android.Manifest.permission.ACCESS_FINE_LOCATION) public android.location.GpsStatus getGpsStatus(@Nullable android.location.GpsStatus);
+    method @Deprecated public void removeGpsStatusListener(android.location.GpsStatus.Listener);
+    method @Deprecated public void removeNmeaListener(android.location.GpsStatus.NmeaListener);
+  }
+
 }
 
 package android.media {
diff --git a/api/system-current.txt b/api/system-current.txt
index 375ce91..260ed3a 100644
--- a/api/system-current.txt
+++ b/api/system-current.txt
@@ -3364,57 +3364,53 @@
   }
 
   public class LocationManager {
-    method @Deprecated public boolean addGpsMeasurementListener(android.location.GpsMeasurementsEvent.Listener);
-    method @Deprecated public boolean addGpsNavigationMessageListener(android.location.GpsNavigationMessageEvent.Listener);
     method @RequiresPermission(android.Manifest.permission.LOCATION_HARDWARE) public void flushGnssBatch();
     method @RequiresPermission(android.Manifest.permission.LOCATION_HARDWARE) public int getGnssBatchSize();
     method public int getGnssCapabilities();
     method @Nullable public String getLocationControllerExtraPackage();
     method @RequiresPermission(android.Manifest.permission.ACCESS_FINE_LOCATION) public void injectGnssMeasurementCorrections(@NonNull android.location.GnssMeasurementCorrections);
     method public boolean isLocationControllerExtraPackageEnabled();
-    method public boolean isLocationEnabledForUser(android.os.UserHandle);
-    method public boolean isProviderEnabledForUser(String, android.os.UserHandle);
-    method public boolean isProviderPackage(String);
-    method @RequiresPermission(android.Manifest.permission.LOCATION_HARDWARE) public boolean registerGnssBatchedLocationCallback(long, boolean, android.location.BatchedLocationCallback, android.os.Handler);
-    method @Deprecated public void removeGpsMeasurementListener(android.location.GpsMeasurementsEvent.Listener);
-    method @Deprecated public void removeGpsNavigationMessageListener(android.location.GpsNavigationMessageEvent.Listener);
-    method @RequiresPermission(anyOf={android.Manifest.permission.ACCESS_COARSE_LOCATION, android.Manifest.permission.ACCESS_FINE_LOCATION}) public void requestLocationUpdates(android.location.LocationRequest, android.location.LocationListener, android.os.Looper);
-    method @RequiresPermission(anyOf={android.Manifest.permission.ACCESS_COARSE_LOCATION, android.Manifest.permission.ACCESS_FINE_LOCATION}) public void requestLocationUpdates(android.location.LocationRequest, android.app.PendingIntent);
-    method @RequiresPermission(android.Manifest.permission.LOCATION_HARDWARE) public void setLocationControllerExtraPackage(String);
+    method public boolean isLocationEnabledForUser(@NonNull android.os.UserHandle);
+    method public boolean isProviderEnabledForUser(@NonNull String, @NonNull android.os.UserHandle);
+    method public boolean isProviderPackage(@NonNull String);
+    method @RequiresPermission(android.Manifest.permission.LOCATION_HARDWARE) public boolean registerGnssBatchedLocationCallback(long, boolean, @NonNull android.location.BatchedLocationCallback, @Nullable android.os.Handler);
+    method @RequiresPermission(anyOf={android.Manifest.permission.ACCESS_COARSE_LOCATION, android.Manifest.permission.ACCESS_FINE_LOCATION}) public void requestLocationUpdates(@NonNull android.location.LocationRequest, @NonNull android.location.LocationListener, @Nullable android.os.Looper);
+    method @RequiresPermission(anyOf={android.Manifest.permission.ACCESS_COARSE_LOCATION, android.Manifest.permission.ACCESS_FINE_LOCATION}) public void requestLocationUpdates(@NonNull android.location.LocationRequest, @NonNull android.app.PendingIntent);
+    method @RequiresPermission(android.Manifest.permission.LOCATION_HARDWARE) public void setLocationControllerExtraPackage(@NonNull String);
     method @RequiresPermission(android.Manifest.permission.LOCATION_HARDWARE) public void setLocationControllerExtraPackageEnabled(boolean);
-    method @RequiresPermission(android.Manifest.permission.WRITE_SECURE_SETTINGS) public void setLocationEnabledForUser(boolean, android.os.UserHandle);
-    method @Deprecated @RequiresPermission(android.Manifest.permission.WRITE_SECURE_SETTINGS) public boolean setProviderEnabledForUser(String, boolean, android.os.UserHandle);
-    method @RequiresPermission(android.Manifest.permission.LOCATION_HARDWARE) public boolean unregisterGnssBatchedLocationCallback(android.location.BatchedLocationCallback);
+    method @RequiresPermission(android.Manifest.permission.WRITE_SECURE_SETTINGS) public void setLocationEnabledForUser(boolean, @NonNull android.os.UserHandle);
+    method @Deprecated @RequiresPermission(android.Manifest.permission.WRITE_SECURE_SETTINGS) public boolean setProviderEnabledForUser(@NonNull String, boolean, @NonNull android.os.UserHandle);
+    method @RequiresPermission(android.Manifest.permission.LOCATION_HARDWARE) public boolean unregisterGnssBatchedLocationCallback(@NonNull android.location.BatchedLocationCallback);
   }
 
   public final class LocationRequest implements android.os.Parcelable {
-    method public static android.location.LocationRequest create();
-    method public static android.location.LocationRequest createFromDeprecatedCriteria(android.location.Criteria, long, float, boolean);
-    method public static android.location.LocationRequest createFromDeprecatedProvider(String, long, float, boolean);
+    method @NonNull public static android.location.LocationRequest create();
+    method @NonNull public static android.location.LocationRequest createFromDeprecatedCriteria(@NonNull android.location.Criteria, long, float, boolean);
+    method @NonNull public static android.location.LocationRequest createFromDeprecatedProvider(@NonNull String, long, float, boolean);
     method public int describeContents();
     method public long getExpireAt();
     method public long getFastestInterval();
     method public boolean getHideFromAppOps();
     method public long getInterval();
     method public int getNumUpdates();
-    method public String getProvider();
+    method @NonNull public String getProvider();
     method public int getQuality();
     method public float getSmallestDisplacement();
-    method public android.os.WorkSource getWorkSource();
+    method @Nullable public android.os.WorkSource getWorkSource();
     method public boolean isLocationSettingsIgnored();
     method public boolean isLowPowerMode();
-    method public android.location.LocationRequest setExpireAt(long);
-    method public android.location.LocationRequest setExpireIn(long);
-    method public android.location.LocationRequest setFastestInterval(long);
+    method @NonNull public android.location.LocationRequest setExpireAt(long);
+    method @NonNull public android.location.LocationRequest setExpireIn(long);
+    method @NonNull public android.location.LocationRequest setFastestInterval(long);
     method public void setHideFromAppOps(boolean);
-    method public android.location.LocationRequest setInterval(long);
-    method @RequiresPermission(android.Manifest.permission.WRITE_SECURE_SETTINGS) public android.location.LocationRequest setLocationSettingsIgnored(boolean);
-    method public android.location.LocationRequest setLowPowerMode(boolean);
-    method public android.location.LocationRequest setNumUpdates(int);
-    method public android.location.LocationRequest setProvider(String);
-    method public android.location.LocationRequest setQuality(int);
-    method public android.location.LocationRequest setSmallestDisplacement(float);
-    method public void setWorkSource(android.os.WorkSource);
+    method @NonNull public android.location.LocationRequest setInterval(long);
+    method @RequiresPermission(android.Manifest.permission.WRITE_SECURE_SETTINGS) @NonNull public android.location.LocationRequest setLocationSettingsIgnored(boolean);
+    method @NonNull public android.location.LocationRequest setLowPowerMode(boolean);
+    method @NonNull public android.location.LocationRequest setNumUpdates(int);
+    method @NonNull public android.location.LocationRequest setProvider(@NonNull String);
+    method @NonNull public android.location.LocationRequest setQuality(int);
+    method @NonNull public android.location.LocationRequest setSmallestDisplacement(float);
+    method public void setWorkSource(@Nullable android.os.WorkSource);
     method public void writeToParcel(android.os.Parcel, int);
     field public static final int ACCURACY_BLOCK = 102; // 0x66
     field public static final int ACCURACY_CITY = 104; // 0x68
diff --git a/api/system-removed.txt b/api/system-removed.txt
index 22a3fb3..7e04469 100644
--- a/api/system-removed.txt
+++ b/api/system-removed.txt
@@ -60,6 +60,17 @@
 
 }
 
+package android.location {
+
+  public class LocationManager {
+    method @Deprecated public boolean addGpsMeasurementListener(android.location.GpsMeasurementsEvent.Listener);
+    method @Deprecated public boolean addGpsNavigationMessageListener(android.location.GpsNavigationMessageEvent.Listener);
+    method @Deprecated public void removeGpsMeasurementListener(android.location.GpsMeasurementsEvent.Listener);
+    method @Deprecated public void removeGpsNavigationMessageListener(android.location.GpsNavigationMessageEvent.Listener);
+  }
+
+}
+
 package android.media.tv {
 
   public final class TvInputManager {
diff --git a/api/test-current.txt b/api/test-current.txt
index 684524e..14e1dba 100644
--- a/api/test-current.txt
+++ b/api/test-current.txt
@@ -936,16 +936,16 @@
   }
 
   public class LocationManager {
-    method public String[] getBackgroundThrottlingWhitelist();
-    method public String[] getIgnoreSettingsWhitelist();
+    method @NonNull public String[] getBackgroundThrottlingWhitelist();
+    method @NonNull public String[] getIgnoreSettingsWhitelist();
     method @NonNull public java.util.List<android.location.LocationRequest> getTestProviderCurrentRequests(String);
-    method @RequiresPermission(anyOf={android.Manifest.permission.ACCESS_COARSE_LOCATION, android.Manifest.permission.ACCESS_FINE_LOCATION}) public void requestLocationUpdates(android.location.LocationRequest, android.location.LocationListener, android.os.Looper);
-    method @RequiresPermission(anyOf={android.Manifest.permission.ACCESS_COARSE_LOCATION, android.Manifest.permission.ACCESS_FINE_LOCATION}) public void requestLocationUpdates(android.location.LocationRequest, android.app.PendingIntent);
-    method @RequiresPermission(android.Manifest.permission.WRITE_SECURE_SETTINGS) public void setLocationEnabledForUser(boolean, android.os.UserHandle);
+    method @RequiresPermission(anyOf={android.Manifest.permission.ACCESS_COARSE_LOCATION, android.Manifest.permission.ACCESS_FINE_LOCATION}) public void requestLocationUpdates(@NonNull android.location.LocationRequest, @NonNull android.location.LocationListener, @Nullable android.os.Looper);
+    method @RequiresPermission(anyOf={android.Manifest.permission.ACCESS_COARSE_LOCATION, android.Manifest.permission.ACCESS_FINE_LOCATION}) public void requestLocationUpdates(@NonNull android.location.LocationRequest, @NonNull android.app.PendingIntent);
+    method @RequiresPermission(android.Manifest.permission.WRITE_SECURE_SETTINGS) public void setLocationEnabledForUser(boolean, @NonNull android.os.UserHandle);
   }
 
   public final class LocationRequest implements android.os.Parcelable {
-    method public static android.location.LocationRequest create();
+    method @NonNull public static android.location.LocationRequest create();
     method public int describeContents();
     method public long getExpireAt();
     method public long getFastestInterval();
@@ -953,14 +953,14 @@
     method public int getNumUpdates();
     method public int getQuality();
     method public boolean isLocationSettingsIgnored();
-    method public android.location.LocationRequest setExpireAt(long);
-    method public android.location.LocationRequest setExpireIn(long);
-    method public android.location.LocationRequest setFastestInterval(long);
-    method public android.location.LocationRequest setInterval(long);
-    method @RequiresPermission(android.Manifest.permission.WRITE_SECURE_SETTINGS) public android.location.LocationRequest setLocationSettingsIgnored(boolean);
-    method public android.location.LocationRequest setNumUpdates(int);
-    method public android.location.LocationRequest setProvider(String);
-    method public android.location.LocationRequest setQuality(int);
+    method @NonNull public android.location.LocationRequest setExpireAt(long);
+    method @NonNull public android.location.LocationRequest setExpireIn(long);
+    method @NonNull public android.location.LocationRequest setFastestInterval(long);
+    method @NonNull public android.location.LocationRequest setInterval(long);
+    method @RequiresPermission(android.Manifest.permission.WRITE_SECURE_SETTINGS) @NonNull public android.location.LocationRequest setLocationSettingsIgnored(boolean);
+    method @NonNull public android.location.LocationRequest setNumUpdates(int);
+    method @NonNull public android.location.LocationRequest setProvider(@NonNull String);
+    method @NonNull public android.location.LocationRequest setQuality(int);
     method public void writeToParcel(android.os.Parcel, int);
     field public static final int ACCURACY_BLOCK = 102; // 0x66
     field public static final int ACCURACY_CITY = 104; // 0x68
diff --git a/location/java/android/location/GpsStatus.java b/location/java/android/location/GpsStatus.java
index 609a15e..4e37654 100644
--- a/location/java/android/location/GpsStatus.java
+++ b/location/java/android/location/GpsStatus.java
@@ -30,6 +30,7 @@
  * <p>This class is used in conjunction with the {@link Listener} interface.
  *
  * @deprecated use {@link GnssStatus} and {@link GnssStatus.Callback}.
+ * @removed
  */
 @Deprecated
 public final class GpsStatus {
@@ -112,6 +113,7 @@
     /**
      * Used for receiving notifications when GPS status has changed.
      * @deprecated use {@link GnssStatus.Callback} instead.
+     * @removed
      */
     @Deprecated
     public interface Listener {
@@ -142,6 +144,7 @@
      * You can implement this interface and call {@link LocationManager#addNmeaListener}
      * to receive NMEA data from the GPS engine.
      * @deprecated use {@link OnNmeaMessageListener} instead.
+     * @removed
      */
     @Deprecated
     public interface NmeaListener {
diff --git a/location/java/android/location/LocationManager.java b/location/java/android/location/LocationManager.java
index 6828c59..8af1532 100644
--- a/location/java/android/location/LocationManager.java
+++ b/location/java/android/location/LocationManager.java
@@ -44,12 +44,12 @@
 import android.os.RemoteException;
 import android.os.UserHandle;
 import android.provider.Settings;
+import android.util.ArrayMap;
 import android.util.Log;
 
 import com.android.internal.location.ProviderProperties;
 
 import java.util.ArrayList;
-import java.util.HashMap;
 import java.util.List;
 
 /**
@@ -78,14 +78,10 @@
     private final GnssMeasurementCallbackTransport mGnssMeasurementCallbackTransport;
     private final GnssNavigationMessageCallbackTransport mGnssNavigationMessageCallbackTransport;
     private final BatchedLocationCallbackTransport mBatchedLocationCallbackTransport;
-    private final HashMap<GpsStatus.Listener, GnssStatusListenerTransport> mGpsStatusListeners =
-            new HashMap<>();
-    private final HashMap<GpsStatus.NmeaListener, GnssStatusListenerTransport> mGpsNmeaListeners =
-            new HashMap<>();
-    private final HashMap<GnssStatus.Callback, GnssStatusListenerTransport> mGnssStatusListeners =
-            new HashMap<>();
-    private final HashMap<OnNmeaMessageListener, GnssStatusListenerTransport> mGnssNmeaListeners =
-            new HashMap<>();
+    private final ArrayMap<GnssStatus.Callback, GnssStatusListenerTransport> mGnssStatusListeners =
+            new ArrayMap<>();
+    private final ArrayMap<OnNmeaMessageListener, GnssStatusListenerTransport> mGnssNmeaListeners =
+            new ArrayMap<>();
     // volatile + GnssStatus final-fields pattern to avoid a partially published object
     private volatile GnssStatus mGnssStatus;
     private int mTimeToFirstFix;
@@ -293,8 +289,7 @@
             "com.android.settings.location.FOOTER_STRING";
 
     // Map from LocationListeners to their associated ListenerTransport objects
-    private final HashMap<LocationListener, ListenerTransport> mListeners =
-        new HashMap<LocationListener,ListenerTransport>();
+    private final ArrayMap<LocationListener, ListenerTransport> mListeners = new ArrayMap<>();
 
     private class ListenerTransport extends ILocationListener.Stub {
         private static final int TYPE_LOCATION_CHANGED = 1;
@@ -405,7 +400,7 @@
      * @hide
      */
     @TestApi
-    public String[] getBackgroundThrottlingWhitelist() {
+    public @NonNull String[] getBackgroundThrottlingWhitelist() {
         try {
             return mService.getBackgroundThrottlingWhitelist();
         } catch (RemoteException e) {
@@ -417,7 +412,7 @@
      * @hide
      */
     @TestApi
-    public String[] getIgnoreSettingsWhitelist() {
+    public @NonNull String[] getIgnoreSettingsWhitelist() {
         try {
             return mService.getIgnoreSettingsWhitelist();
         } catch (RemoteException e) {
@@ -431,7 +426,7 @@
      * right way to create an instance of this class is using the
      * factory Context.getSystemService.
      */
-    public LocationManager(Context context, ILocationManager service) {
+    public LocationManager(@NonNull Context context, @NonNull ILocationManager service) {
         mService = service;
         mContext = context;
         mGnssMeasurementCallbackTransport =
@@ -454,7 +449,7 @@
      *
      * @return list of Strings containing names of the provider
      */
-    public List<String> getAllProviders() {
+    public @NonNull List<String> getAllProviders() {
         try {
             return mService.getAllProviders();
         } catch (RemoteException e) {
@@ -469,7 +464,7 @@
      * enabled are returned.
      * @return list of Strings containing names of the providers
      */
-    public List<String> getProviders(boolean enabledOnly) {
+    public @NonNull List<String> getProviders(boolean enabledOnly) {
         try {
             return mService.getProviders(null, enabledOnly);
         } catch (RemoteException e) {
@@ -488,7 +483,7 @@
      * @throws SecurityException if the caller is not permitted to access the
      * given provider.
      */
-    public LocationProvider getProvider(String name) {
+    public @Nullable LocationProvider getProvider(@NonNull String name) {
         checkProvider(name);
         try {
             ProviderProperties properties = mService.getProviderProperties(name);
@@ -511,7 +506,7 @@
      * enabled are returned.
      * @return list of Strings containing names of the providers
      */
-    public List<String> getProviders(Criteria criteria, boolean enabledOnly) {
+    public @NonNull List<String> getProviders(@NonNull Criteria criteria, boolean enabledOnly) {
         checkCriteria(criteria);
         try {
             return mService.getProviders(criteria, enabledOnly);
@@ -542,7 +537,7 @@
      * @param enabledOnly if true then only a provider that is currently enabled is returned
      * @return name of the provider that best matches the requirements
      */
-    public String getBestProvider(Criteria criteria, boolean enabledOnly) {
+    public @Nullable String getBestProvider(@NonNull Criteria criteria, boolean enabledOnly) {
         checkCriteria(criteria);
         try {
             return mService.getBestProvider(criteria, enabledOnly);
@@ -572,8 +567,8 @@
      * @throws SecurityException if no suitable permission is present
      */
     @RequiresPermission(anyOf = {ACCESS_COARSE_LOCATION, ACCESS_FINE_LOCATION})
-    public void requestLocationUpdates(String provider, long minTime, float minDistance,
-            LocationListener listener) {
+    public void requestLocationUpdates(@NonNull String provider, long minTime, float minDistance,
+            @NonNull LocationListener listener) {
         checkProvider(provider);
         checkListener(listener);
 
@@ -604,8 +599,8 @@
      * @throws SecurityException if no suitable permission is present
      */
     @RequiresPermission(anyOf = {ACCESS_COARSE_LOCATION, ACCESS_FINE_LOCATION})
-    public void requestLocationUpdates(String provider, long minTime, float minDistance,
-            LocationListener listener, Looper looper) {
+    public void requestLocationUpdates(@NonNull String provider, long minTime, float minDistance,
+            @NonNull LocationListener listener, @Nullable Looper looper) {
         checkProvider(provider);
         checkListener(listener);
 
@@ -637,8 +632,8 @@
      * @throws SecurityException if no suitable permission is present
      */
     @RequiresPermission(anyOf = {ACCESS_COARSE_LOCATION, ACCESS_FINE_LOCATION})
-    public void requestLocationUpdates(long minTime, float minDistance, Criteria criteria,
-            LocationListener listener, Looper looper) {
+    public void requestLocationUpdates(long minTime, float minDistance, @NonNull Criteria criteria,
+            @NonNull LocationListener listener, @Nullable Looper looper) {
         checkCriteria(criteria);
         checkListener(listener);
 
@@ -665,8 +660,8 @@
      * @throws SecurityException if no suitable permission is present
      */
     @RequiresPermission(anyOf = {ACCESS_COARSE_LOCATION, ACCESS_FINE_LOCATION})
-    public void requestLocationUpdates(String provider, long minTime, float minDistance,
-            PendingIntent intent) {
+    public void requestLocationUpdates(@NonNull String provider, long minTime, float minDistance,
+            @NonNull PendingIntent intent) {
         checkProvider(provider);
         checkPendingIntent(intent);
 
@@ -772,8 +767,8 @@
      * @throws SecurityException if no suitable permission is present
      */
     @RequiresPermission(anyOf = {ACCESS_COARSE_LOCATION, ACCESS_FINE_LOCATION})
-    public void requestLocationUpdates(long minTime, float minDistance, Criteria criteria,
-            PendingIntent intent) {
+    public void requestLocationUpdates(long minTime, float minDistance, @NonNull Criteria criteria,
+            @NonNull PendingIntent intent) {
         checkCriteria(criteria);
         checkPendingIntent(intent);
 
@@ -802,7 +797,8 @@
      * @throws SecurityException if no suitable permission is present
      */
     @RequiresPermission(anyOf = {ACCESS_COARSE_LOCATION, ACCESS_FINE_LOCATION})
-    public void requestSingleUpdate(String provider, LocationListener listener, Looper looper) {
+    public void requestSingleUpdate(
+            @NonNull String provider, @NonNull LocationListener listener, @Nullable Looper looper) {
         checkProvider(provider);
         checkListener(listener);
 
@@ -832,7 +828,10 @@
      * @throws SecurityException if no suitable permission is present
      */
     @RequiresPermission(anyOf = {ACCESS_COARSE_LOCATION, ACCESS_FINE_LOCATION})
-    public void requestSingleUpdate(Criteria criteria, LocationListener listener, Looper looper) {
+    public void requestSingleUpdate(
+            @NonNull Criteria criteria,
+            @NonNull LocationListener listener,
+            @Nullable Looper looper) {
         checkCriteria(criteria);
         checkListener(listener);
 
@@ -855,7 +854,7 @@
      * @throws SecurityException if no suitable permission is present
      */
     @RequiresPermission(anyOf = {ACCESS_COARSE_LOCATION, ACCESS_FINE_LOCATION})
-    public void requestSingleUpdate(String provider, PendingIntent intent) {
+    public void requestSingleUpdate(@NonNull String provider, @NonNull PendingIntent intent) {
         checkProvider(provider);
         checkPendingIntent(intent);
 
@@ -879,7 +878,7 @@
      * @throws SecurityException if no suitable permission is present
      */
     @RequiresPermission(anyOf = {ACCESS_COARSE_LOCATION, ACCESS_FINE_LOCATION})
-    public void requestSingleUpdate(Criteria criteria, PendingIntent intent) {
+    public void requestSingleUpdate(@NonNull Criteria criteria, @NonNull PendingIntent intent) {
         checkCriteria(criteria);
         checkPendingIntent(intent);
 
@@ -948,8 +947,10 @@
     @SystemApi
     @TestApi
     @RequiresPermission(anyOf = {ACCESS_COARSE_LOCATION, ACCESS_FINE_LOCATION})
-    public void requestLocationUpdates(LocationRequest request, LocationListener listener,
-            Looper looper) {
+    public void requestLocationUpdates(
+            @NonNull LocationRequest request,
+            @NonNull LocationListener listener,
+            @Nullable Looper looper) {
         checkListener(listener);
         requestLocationUpdates(request, listener, looper, null);
     }
@@ -978,7 +979,8 @@
     @SystemApi
     @TestApi
     @RequiresPermission(anyOf = {ACCESS_COARSE_LOCATION, ACCESS_FINE_LOCATION})
-    public void requestLocationUpdates(LocationRequest request, PendingIntent intent) {
+    public void requestLocationUpdates(
+            @NonNull LocationRequest request, @NonNull PendingIntent intent) {
         checkPendingIntent(intent);
         requestLocationUpdates(request, null, null, intent);
     }
@@ -1003,7 +1005,7 @@
      * @hide
      */
     @RequiresPermission(allOf = {LOCATION_HARDWARE, ACCESS_FINE_LOCATION})
-    public boolean injectLocation(Location newLocation) {
+    public boolean injectLocation(@NonNull Location newLocation) {
         try {
             return mService.injectLocation(newLocation);
         } catch (RemoteException e) {
@@ -1048,7 +1050,7 @@
      * @param listener listener object that no longer needs location updates
      * @throws IllegalArgumentException if listener is null
      */
-    public void removeUpdates(LocationListener listener) {
+    public void removeUpdates(@NonNull LocationListener listener) {
         checkListener(listener);
         String packageName = mContext.getPackageName();
 
@@ -1073,7 +1075,7 @@
      * @param intent pending intent object that no longer needs location updates
      * @throws IllegalArgumentException if intent is null
      */
-    public void removeUpdates(PendingIntent intent) {
+    public void removeUpdates(@NonNull PendingIntent intent) {
         checkPendingIntent(intent);
         String packageName = mContext.getPackageName();
 
@@ -1133,7 +1135,7 @@
      */
     @RequiresPermission(anyOf = {ACCESS_COARSE_LOCATION, ACCESS_FINE_LOCATION})
     public void addProximityAlert(double latitude, double longitude, float radius, long expiration,
-            PendingIntent intent) {
+            @NonNull PendingIntent intent) {
         checkPendingIntent(intent);
         if (expiration < 0) expiration = Long.MAX_VALUE;
 
@@ -1183,7 +1185,10 @@
      * @hide
      */
     @RequiresPermission(anyOf = {ACCESS_COARSE_LOCATION, ACCESS_FINE_LOCATION})
-    public void addGeofence(LocationRequest request, Geofence fence, PendingIntent intent) {
+    public void addGeofence(
+            @NonNull LocationRequest request,
+            @NonNull Geofence fence,
+            @NonNull PendingIntent intent) {
         checkPendingIntent(intent);
         checkGeofence(fence);
 
@@ -1210,7 +1215,7 @@
      * @throws SecurityException if {@link android.Manifest.permission#ACCESS_FINE_LOCATION}
      * permission is not present
      */
-    public void removeProximityAlert(PendingIntent intent) {
+    public void removeProximityAlert(@NonNull PendingIntent intent) {
         checkPendingIntent(intent);
         String packageName = mContext.getPackageName();
 
@@ -1237,7 +1242,7 @@
      *
      * @hide
      */
-    public void removeGeofence(Geofence fence, PendingIntent intent) {
+    public void removeGeofence(@NonNull Geofence fence, @NonNull PendingIntent intent) {
         checkPendingIntent(intent);
         checkGeofence(fence);
         String packageName = mContext.getPackageName();
@@ -1260,7 +1265,7 @@
      *
      * @hide
      */
-    public void removeAllGeofences(PendingIntent intent) {
+    public void removeAllGeofences(@NonNull PendingIntent intent) {
         checkPendingIntent(intent);
         String packageName = mContext.getPackageName();
 
@@ -1290,7 +1295,7 @@
      * @hide
      */
     @SystemApi
-    public boolean isLocationEnabledForUser(UserHandle userHandle) {
+    public boolean isLocationEnabledForUser(@NonNull UserHandle userHandle) {
         try {
             return mService.isLocationEnabledForUser(userHandle.getIdentifier());
         } catch (RemoteException e) {
@@ -1309,7 +1314,7 @@
     @SystemApi
     @TestApi
     @RequiresPermission(WRITE_SECURE_SETTINGS)
-    public void setLocationEnabledForUser(boolean enabled, UserHandle userHandle) {
+    public void setLocationEnabledForUser(boolean enabled, @NonNull UserHandle userHandle) {
         Settings.Secure.putIntForUser(
                 mContext.getContentResolver(),
                 Settings.Secure.LOCATION_MODE,
@@ -1332,7 +1337,7 @@
      *
      * @throws IllegalArgumentException if provider is null
      */
-    public boolean isProviderEnabled(String provider) {
+    public boolean isProviderEnabled(@NonNull String provider) {
         return isProviderEnabledForUser(provider, Process.myUserHandle());
     }
 
@@ -1353,7 +1358,8 @@
      * @hide
      */
     @SystemApi
-    public boolean isProviderEnabledForUser(String provider, UserHandle userHandle) {
+    public boolean isProviderEnabledForUser(
+            @NonNull String provider, @NonNull UserHandle userHandle) {
         checkProvider(provider);
 
         try {
@@ -1382,7 +1388,7 @@
     @SystemApi
     @RequiresPermission(WRITE_SECURE_SETTINGS)
     public boolean setProviderEnabledForUser(
-            String provider, boolean enabled, UserHandle userHandle) {
+            @NonNull String provider, boolean enabled, @NonNull UserHandle userHandle) {
         checkProvider(provider);
 
         return Settings.Secure.setLocationProviderEnabledForUser(
@@ -1406,6 +1412,7 @@
      *
      * @hide
      */
+    @Nullable
     public Location getLastLocation() {
         String packageName = mContext.getPackageName();
 
@@ -1434,7 +1441,8 @@
      * @throws IllegalArgumentException if provider is null or doesn't exist
      */
     @RequiresPermission(anyOf = {ACCESS_COARSE_LOCATION, ACCESS_FINE_LOCATION})
-    public Location getLastKnownLocation(String provider) {
+    @Nullable
+    public Location getLastKnownLocation(@NonNull String provider) {
         checkProvider(provider);
         String packageName = mContext.getPackageName();
         LocationRequest request = LocationRequest.createFromDeprecatedProvider(
@@ -1447,10 +1455,6 @@
         }
     }
 
-    // --- Mock provider support ---
-    // TODO: It would be fantastic to deprecate mock providers entirely, and replace
-    // with something closer to LocationProviderBase.java
-
     /**
      * Creates a mock location provider and adds it to the set of active providers.
      *
@@ -1461,7 +1465,8 @@
      * allowed} for your app.
      * @throws IllegalArgumentException if a provider with the given name already exists
      */
-    public void addTestProvider(String name, boolean requiresNetwork, boolean requiresSatellite,
+    public void addTestProvider(
+            @NonNull String name, boolean requiresNetwork, boolean requiresSatellite,
             boolean requiresCell, boolean hasMonetaryCost, boolean supportsAltitude,
             boolean supportsSpeed, boolean supportsBearing, int powerRequirement, int accuracy) {
         ProviderProperties properties = new ProviderProperties(requiresNetwork,
@@ -1488,7 +1493,7 @@
      * allowed} for your app.
      * @throws IllegalArgumentException if no provider with the given name exists
      */
-    public void removeTestProvider(String provider) {
+    public void removeTestProvider(@NonNull String provider) {
         try {
             mService.removeTestProvider(provider, mContext.getOpPackageName());
         } catch (RemoteException e) {
@@ -1512,7 +1517,7 @@
      * @throws IllegalArgumentException if no provider with the given name exists
      * @throws IllegalArgumentException if the location is incomplete
      */
-    public void setTestProviderLocation(String provider, Location loc) {
+    public void setTestProviderLocation(@NonNull String provider, @NonNull Location loc) {
         if (!loc.isComplete()) {
             IllegalArgumentException e = new IllegalArgumentException(
                     "Incomplete location object, missing timestamp or accuracy? " + loc);
@@ -1546,7 +1551,7 @@
      * @deprecated This function has always been a no-op, and may be removed in the future.
      */
     @Deprecated
-    public void clearTestProviderLocation(String provider) {}
+    public void clearTestProviderLocation(@NonNull String provider) {}
 
     /**
      * Sets a mock enabled value for the given provider.  This value will be used in place
@@ -1560,7 +1565,7 @@
      * allowed} for your app.
      * @throws IllegalArgumentException if no provider with the given name exists
      */
-    public void setTestProviderEnabled(String provider, boolean enabled) {
+    public void setTestProviderEnabled(@NonNull String provider, boolean enabled) {
         try {
             mService.setTestProviderEnabled(provider, enabled, mContext.getOpPackageName());
         } catch (RemoteException e) {
@@ -1581,7 +1586,7 @@
      * @deprecated Use {@link #setTestProviderEnabled(String, boolean)} instead.
      */
     @Deprecated
-    public void clearTestProviderEnabled(String provider) {
+    public void clearTestProviderEnabled(@NonNull String provider) {
         setTestProviderEnabled(provider, false);
     }
 
@@ -1601,7 +1606,8 @@
      * @deprecated This method has no effect.
      */
     @Deprecated
-    public void setTestProviderStatus(String provider, int status, Bundle extras, long updateTime) {
+    public void setTestProviderStatus(
+            @NonNull String provider, int status, @Nullable Bundle extras, long updateTime) {
         try {
             mService.setTestProviderStatus(provider, status, extras, updateTime,
                     mContext.getOpPackageName());
@@ -1622,7 +1628,7 @@
      * @deprecated This method has no effect.
      */
     @Deprecated
-    public void clearTestProviderStatus(String provider) {
+    public void clearTestProviderStatus(@NonNull String provider) {
         setTestProviderStatus(provider, LocationProvider.AVAILABLE, null, 0L);
     }
 
@@ -1648,13 +1654,11 @@
     // This class is used to send Gnss status events to the client's specific thread.
     private class GnssStatusListenerTransport extends IGnssStatusListener.Stub {
 
-        private final GpsStatus.Listener mGpsListener;
-        private final GpsStatus.NmeaListener mGpsNmeaListener;
         private final GnssStatus.Callback mGnssCallback;
         private final OnNmeaMessageListener mGnssNmeaListener;
 
         private class GnssHandler extends Handler {
-            public GnssHandler(Handler handler) {
+            GnssHandler(Handler handler) {
                 super(handler != null ? handler.getLooper() : Looper.myLooper());
             }
 
@@ -1663,24 +1667,22 @@
                 switch (msg.what) {
                     case NMEA_RECEIVED:
                         synchronized (mNmeaBuffer) {
-                            int length = mNmeaBuffer.size();
-                            for (int i = 0; i < length; i++) {
-                                Nmea nmea = mNmeaBuffer.get(i);
+                            for (Nmea nmea : mNmeaBuffer) {
                                 mGnssNmeaListener.onNmeaMessage(nmea.mNmea, nmea.mTimestamp);
                             }
                             mNmeaBuffer.clear();
                         }
                         break;
-                    case GpsStatus.GPS_EVENT_STARTED:
+                    case GNSS_EVENT_STARTED:
                         mGnssCallback.onStarted();
                         break;
-                    case GpsStatus.GPS_EVENT_STOPPED:
+                    case GNSS_EVENT_STOPPED:
                         mGnssCallback.onStopped();
                         break;
-                    case GpsStatus.GPS_EVENT_FIRST_FIX:
+                    case GNSS_EVENT_FIRST_FIX:
                         mGnssCallback.onFirstFix(mTimeToFirstFix);
                         break;
-                    case GpsStatus.GPS_EVENT_SATELLITE_STATUS:
+                    case GNSS_EVENT_SATELLITE_STATUS:
                         mGnssCallback.onSatelliteStatusChanged(mGnssStatus);
                         break;
                     default:
@@ -1691,8 +1693,11 @@
 
         private final Handler mGnssHandler;
 
-        // This must not equal any of the GpsStatus event IDs
-        private static final int NMEA_RECEIVED = 1000;
+        private static final int NMEA_RECEIVED = 1;
+        private static final int GNSS_EVENT_STARTED = 2;
+        private static final int GNSS_EVENT_STOPPED = 3;
+        private static final int GNSS_EVENT_FIRST_FIX = 4;
+        private static final int GNSS_EVENT_SATELLITE_STATUS = 5;
 
         private class Nmea {
             long mTimestamp;
@@ -1705,98 +1710,31 @@
         }
         private final ArrayList<Nmea> mNmeaBuffer;
 
-        GnssStatusListenerTransport(GpsStatus.Listener listener) {
-            this(listener, null);
-        }
-
-        GnssStatusListenerTransport(GpsStatus.Listener listener, Handler handler) {
-            mGpsListener = listener;
-            mGnssHandler = new GnssHandler(handler);
-            mGpsNmeaListener = null;
-            mNmeaBuffer = null;
-            mGnssCallback = mGpsListener != null ? new GnssStatus.Callback() {
-                @Override
-                public void onStarted() {
-                    mGpsListener.onGpsStatusChanged(GpsStatus.GPS_EVENT_STARTED);
-                }
-
-                @Override
-                public void onStopped() {
-                    mGpsListener.onGpsStatusChanged(GpsStatus.GPS_EVENT_STOPPED);
-                }
-
-                @Override
-                public void onFirstFix(int ttff) {
-                    mGpsListener.onGpsStatusChanged(GpsStatus.GPS_EVENT_FIRST_FIX);
-                }
-
-                @Override
-                public void onSatelliteStatusChanged(GnssStatus status) {
-                    mGpsListener.onGpsStatusChanged(GpsStatus.GPS_EVENT_SATELLITE_STATUS);
-                }
-            } : null;
-            mGnssNmeaListener = null;
-        }
-
-        GnssStatusListenerTransport(GpsStatus.NmeaListener listener) {
-            this(listener, null);
-        }
-
-        GnssStatusListenerTransport(GpsStatus.NmeaListener listener, Handler handler) {
-            mGpsListener = null;
-            mGnssHandler = new GnssHandler(handler);
-            mGpsNmeaListener = listener;
-            mNmeaBuffer = new ArrayList<Nmea>();
-            mGnssCallback = null;
-            mGnssNmeaListener = mGpsNmeaListener != null ? new OnNmeaMessageListener() {
-                @Override
-                public void onNmeaMessage(String nmea, long timestamp) {
-                    mGpsNmeaListener.onNmeaReceived(timestamp, nmea);
-                }
-            } : null;
-        }
-
-        GnssStatusListenerTransport(GnssStatus.Callback callback) {
-            this(callback, null);
-        }
-
         GnssStatusListenerTransport(GnssStatus.Callback callback, Handler handler) {
             mGnssCallback = callback;
             mGnssHandler = new GnssHandler(handler);
             mGnssNmeaListener = null;
             mNmeaBuffer = null;
-            mGpsListener = null;
-            mGpsNmeaListener = null;
-        }
-
-        GnssStatusListenerTransport(OnNmeaMessageListener listener) {
-            this(listener, null);
         }
 
         GnssStatusListenerTransport(OnNmeaMessageListener listener, Handler handler) {
             mGnssCallback = null;
             mGnssHandler = new GnssHandler(handler);
             mGnssNmeaListener = listener;
-            mGpsListener = null;
-            mGpsNmeaListener = null;
-            mNmeaBuffer = new ArrayList<Nmea>();
+            mNmeaBuffer = new ArrayList<>();
         }
 
         @Override
         public void onGnssStarted() {
             if (mGnssCallback != null) {
-                Message msg = Message.obtain();
-                msg.what = GpsStatus.GPS_EVENT_STARTED;
-                mGnssHandler.sendMessage(msg);
+                mGnssHandler.obtainMessage(GNSS_EVENT_STARTED).sendToTarget();
             }
         }
 
         @Override
         public void onGnssStopped() {
             if (mGnssCallback != null) {
-                Message msg = Message.obtain();
-                msg.what = GpsStatus.GPS_EVENT_STOPPED;
-                mGnssHandler.sendMessage(msg);
+                mGnssHandler.obtainMessage(GNSS_EVENT_STOPPED).sendToTarget();
             }
         }
 
@@ -1804,9 +1742,7 @@
         public void onFirstFix(int ttff) {
             if (mGnssCallback != null) {
                 mTimeToFirstFix = ttff;
-                Message msg = Message.obtain();
-                msg.what = GpsStatus.GPS_EVENT_FIRST_FIX;
-                mGnssHandler.sendMessage(msg);
+                mGnssHandler.obtainMessage(GNSS_EVENT_FIRST_FIX).sendToTarget();
             }
         }
 
@@ -1817,11 +1753,8 @@
                 mGnssStatus = new GnssStatus(svCount, prnWithFlags, cn0s, elevations, azimuths,
                         carrierFreqs);
 
-                Message msg = Message.obtain();
-                msg.what = GpsStatus.GPS_EVENT_SATELLITE_STATUS;
-                // remove any SV status messages already in the queue
-                mGnssHandler.removeMessages(GpsStatus.GPS_EVENT_SATELLITE_STATUS);
-                mGnssHandler.sendMessage(msg);
+                mGnssHandler.removeMessages(GNSS_EVENT_SATELLITE_STATUS);
+                mGnssHandler.obtainMessage(GNSS_EVENT_SATELLITE_STATUS).sendToTarget();
             }
         }
 
@@ -1831,11 +1764,9 @@
                 synchronized (mNmeaBuffer) {
                     mNmeaBuffer.add(new Nmea(timestamp, nmea));
                 }
-                Message msg = Message.obtain();
-                msg.what = NMEA_RECEIVED;
-                // remove any NMEA_RECEIVED messages already in the queue
+
                 mGnssHandler.removeMessages(NMEA_RECEIVED);
-                mGnssHandler.sendMessage(msg);
+                mGnssHandler.obtainMessage(NMEA_RECEIVED).sendToTarget();
             }
         }
     }
@@ -1849,27 +1780,12 @@
      *
      * @throws SecurityException if the ACCESS_FINE_LOCATION permission is not present
      * @deprecated use {@link #registerGnssStatusCallback(GnssStatus.Callback)} instead.
+     * @removed
      */
     @Deprecated
     @RequiresPermission(ACCESS_FINE_LOCATION)
     public boolean addGpsStatusListener(GpsStatus.Listener listener) {
-        boolean result;
-
-        if (mGpsStatusListeners.get(listener) != null) {
-            // listener is already registered
-            return true;
-        }
-        try {
-            GnssStatusListenerTransport transport = new GnssStatusListenerTransport(listener);
-            result = mService.registerGnssStatusCallback(transport, mContext.getPackageName());
-            if (result) {
-                mGpsStatusListeners.put(listener, transport);
-            }
-        } catch (RemoteException e) {
-            throw e.rethrowFromSystemServer();
-        }
-
-        return result;
+        return false;
     }
 
     /**
@@ -1877,18 +1793,10 @@
      *
      * @param listener GPS status listener object to remove
      * @deprecated use {@link #unregisterGnssStatusCallback(GnssStatus.Callback)} instead.
+     * @removed
      */
     @Deprecated
-    public void removeGpsStatusListener(GpsStatus.Listener listener) {
-        try {
-            GnssStatusListenerTransport transport = mGpsStatusListeners.remove(listener);
-            if (transport != null) {
-                mService.unregisterGnssStatusCallback(transport);
-            }
-        } catch (RemoteException e) {
-            throw e.rethrowFromSystemServer();
-        }
-    }
+    public void removeGpsStatusListener(GpsStatus.Listener listener) {}
 
     /**
      * Registers a GNSS status callback.
@@ -1900,7 +1808,7 @@
      * @throws SecurityException if the ACCESS_FINE_LOCATION permission is not present
      */
     @RequiresPermission(ACCESS_FINE_LOCATION)
-    public boolean registerGnssStatusCallback(GnssStatus.Callback callback) {
+    public boolean registerGnssStatusCallback(@NonNull GnssStatus.Callback callback) {
         return registerGnssStatusCallback(callback, null);
     }
 
@@ -1915,7 +1823,8 @@
      * @throws SecurityException if the ACCESS_FINE_LOCATION permission is not present
      */
     @RequiresPermission(ACCESS_FINE_LOCATION)
-    public boolean registerGnssStatusCallback(GnssStatus.Callback callback, Handler handler) {
+    public boolean registerGnssStatusCallback(
+            @NonNull GnssStatus.Callback callback, @Nullable Handler handler) {
         boolean result;
         if (mGnssStatusListeners.get(callback) != null) {
             // listener is already registered
@@ -1940,7 +1849,7 @@
      *
      * @param callback GNSS status callback object to remove
      */
-    public void unregisterGnssStatusCallback(GnssStatus.Callback callback) {
+    public void unregisterGnssStatusCallback(@NonNull GnssStatus.Callback callback) {
         try {
             GnssStatusListenerTransport transport = mGnssStatusListeners.remove(callback);
             if (transport != null) {
@@ -1960,27 +1869,12 @@
      *
      * @throws SecurityException if the ACCESS_FINE_LOCATION permission is not present
      * @deprecated use {@link #addNmeaListener(OnNmeaMessageListener)} instead.
+     * @removed
      */
     @Deprecated
     @RequiresPermission(ACCESS_FINE_LOCATION)
     public boolean addNmeaListener(GpsStatus.NmeaListener listener) {
-        boolean result;
-
-        if (mGpsNmeaListeners.get(listener) != null) {
-            // listener is already registered
-            return true;
-        }
-        try {
-            GnssStatusListenerTransport transport = new GnssStatusListenerTransport(listener);
-            result = mService.registerGnssStatusCallback(transport, mContext.getPackageName());
-            if (result) {
-                mGpsNmeaListeners.put(listener, transport);
-            }
-        } catch (RemoteException e) {
-            throw e.rethrowFromSystemServer();
-        }
-
-        return result;
+        return false;
     }
 
     /**
@@ -1988,18 +1882,10 @@
      *
      * @param listener a {@link GpsStatus.NmeaListener} object to remove
      * @deprecated use {@link #removeNmeaListener(OnNmeaMessageListener)} instead.
+     * @removed
      */
     @Deprecated
-    public void removeNmeaListener(GpsStatus.NmeaListener listener) {
-        try {
-            GnssStatusListenerTransport transport = mGpsNmeaListeners.remove(listener);
-            if (transport != null) {
-                mService.unregisterGnssStatusCallback(transport);
-            }
-        } catch (RemoteException e) {
-            throw e.rethrowFromSystemServer();
-        }
-    }
+    public void removeNmeaListener(GpsStatus.NmeaListener listener) {}
 
     /**
      * Adds an NMEA listener.
@@ -2011,7 +1897,7 @@
      * @throws SecurityException if the ACCESS_FINE_LOCATION permission is not present
      */
     @RequiresPermission(ACCESS_FINE_LOCATION)
-    public boolean addNmeaListener(OnNmeaMessageListener listener) {
+    public boolean addNmeaListener(@NonNull OnNmeaMessageListener listener) {
         return addNmeaListener(listener, null);
     }
 
@@ -2026,10 +1912,11 @@
      * @throws SecurityException if the ACCESS_FINE_LOCATION permission is not present
      */
     @RequiresPermission(ACCESS_FINE_LOCATION)
-    public boolean addNmeaListener(OnNmeaMessageListener listener, Handler handler) {
+    public boolean addNmeaListener(
+            @NonNull OnNmeaMessageListener listener, @Nullable Handler handler) {
         boolean result;
 
-        if (mGpsNmeaListeners.get(listener) != null) {
+        if (mGnssNmeaListeners.get(listener) != null) {
             // listener is already registered
             return true;
         }
@@ -2052,7 +1939,7 @@
      *
      * @param listener a {@link OnNmeaMessageListener} object to remove
      */
-    public void removeNmeaListener(OnNmeaMessageListener listener) {
+    public void removeNmeaListener(@NonNull OnNmeaMessageListener listener) {
         try {
             GnssStatusListenerTransport transport = mGnssNmeaListeners.remove(listener);
             if (transport != null) {
@@ -2068,6 +1955,7 @@
      * Don't use it. Use {@link #registerGnssMeasurementsCallback} instead.
      * @hide
      * @deprecated Not supported anymore.
+     * @removed
      */
     @Deprecated
     @SystemApi
@@ -2083,7 +1971,8 @@
      * @return {@code true} if the callback was added successfully, {@code false} otherwise.
      */
     @RequiresPermission(ACCESS_FINE_LOCATION)
-    public boolean registerGnssMeasurementsCallback(GnssMeasurementsEvent.Callback callback) {
+    public boolean registerGnssMeasurementsCallback(
+            @NonNull GnssMeasurementsEvent.Callback callback) {
         return registerGnssMeasurementsCallback(callback, null);
     }
 
@@ -2095,8 +1984,8 @@
      * @return {@code true} if the callback was added successfully, {@code false} otherwise.
      */
     @RequiresPermission(ACCESS_FINE_LOCATION)
-    public boolean registerGnssMeasurementsCallback(GnssMeasurementsEvent.Callback callback,
-            Handler handler) {
+    public boolean registerGnssMeasurementsCallback(
+            @NonNull GnssMeasurementsEvent.Callback callback, @Nullable Handler handler) {
         return mGnssMeasurementCallbackTransport.add(callback, handler);
     }
 
@@ -2120,15 +2009,12 @@
     }
 
     /**
-     * Returns an integer with flags representing the capabilities of the GNSS chipset.
+     * Returns the integer capability flags of the GNSS chipset as defined in {@code
+     * IGnssCallback.hal}
      *
      * @hide
      */
     @SystemApi
-    /**
-     * Returns the integer capability flags of the GNSS chipset as defined in {@code
-     * IGnssCallback.hal}
-     */
     public int getGnssCapabilities() {
         try {
             return mGnssMeasurementCallbackTransport.getGnssCapabilities();
@@ -2144,6 +2030,7 @@
      * @hide
      * @deprecated use {@link #unregisterGnssMeasurementsCallback(GnssMeasurementsEvent.Callback)}
      *     instead.
+     * @removed
      */
     @Deprecated
     @SystemApi
@@ -2155,7 +2042,8 @@
      *
      * @param callback a {@link GnssMeasurementsEvent.Callback} object to remove.
      */
-    public void unregisterGnssMeasurementsCallback(GnssMeasurementsEvent.Callback callback) {
+    public void unregisterGnssMeasurementsCallback(
+            @NonNull GnssMeasurementsEvent.Callback callback) {
         mGnssMeasurementCallbackTransport.remove(callback);
     }
 
@@ -2164,6 +2052,7 @@
      * Don't use it. Use {@link #registerGnssNavigationMessageCallback} instead.
      * @hide
      * @deprecated Not supported anymore.
+     * @removed
      */
     @Deprecated
     @SystemApi
@@ -2179,12 +2068,12 @@
      * @deprecated use
      * {@link #unregisterGnssNavigationMessageCallback(GnssNavigationMessage.Callback)}
      * instead
+     * @removed
      */
     @Deprecated
     @SystemApi
     @SuppressLint("Doclava125")
-    public void removeGpsNavigationMessageListener(GpsNavigationMessageEvent.Listener listener) {
-    }
+    public void removeGpsNavigationMessageListener(GpsNavigationMessageEvent.Listener listener) {}
 
     /**
      * Registers a GNSS Navigation Message callback.
@@ -2193,7 +2082,7 @@
      * @return {@code true} if the callback was added successfully, {@code false} otherwise.
      */
     public boolean registerGnssNavigationMessageCallback(
-            GnssNavigationMessage.Callback callback) {
+            @NonNull GnssNavigationMessage.Callback callback) {
         return registerGnssNavigationMessageCallback(callback, null);
     }
 
@@ -2206,7 +2095,7 @@
      */
     @RequiresPermission(ACCESS_FINE_LOCATION)
     public boolean registerGnssNavigationMessageCallback(
-            GnssNavigationMessage.Callback callback, Handler handler) {
+            @NonNull GnssNavigationMessage.Callback callback, @Nullable Handler handler) {
         return mGnssNavigationMessageCallbackTransport.add(callback, handler);
     }
 
@@ -2216,7 +2105,7 @@
      * @param callback a {@link GnssNavigationMessage.Callback} object to remove.
      */
     public void unregisterGnssNavigationMessageCallback(
-            GnssNavigationMessage.Callback callback) {
+            @NonNull GnssNavigationMessage.Callback callback) {
         mGnssNavigationMessageCallbackTransport.remove(callback);
     }
 
@@ -2230,19 +2119,12 @@
      *
      * @param status object containing GPS status details, or null.
      * @return status object containing updated GPS status.
+     * @removed
      */
     @Deprecated
     @RequiresPermission(ACCESS_FINE_LOCATION)
-    public GpsStatus getGpsStatus(GpsStatus status) {
-        if (status == null) {
-            status = new GpsStatus();
-        }
-        // When mGnssStatus is null, that means that this method is called outside
-        // onGpsStatusChanged().  Return an empty status to maintain backwards compatibility.
-        if (mGnssStatus != null) {
-            status.setStatus(mGnssStatus, mTimeToFirstFix);
-        }
-        return status;
+    public @Nullable GpsStatus getGpsStatus(@Nullable GpsStatus status) {
+        return null;
     }
 
     /**
@@ -2319,7 +2201,7 @@
     @SystemApi
     @RequiresPermission(Manifest.permission.LOCATION_HARDWARE)
     public boolean registerGnssBatchedLocationCallback(long periodNanos, boolean wakeOnFifoFull,
-                                  BatchedLocationCallback callback, Handler handler) {
+            @NonNull BatchedLocationCallback callback, @Nullable Handler handler) {
         mBatchedLocationCallbackTransport.add(callback, handler);
 
         try {
@@ -2357,7 +2239,8 @@
      */
     @SystemApi
     @RequiresPermission(Manifest.permission.LOCATION_HARDWARE)
-    public boolean unregisterGnssBatchedLocationCallback(BatchedLocationCallback callback) {
+    public boolean unregisterGnssBatchedLocationCallback(
+            @NonNull BatchedLocationCallback callback) {
 
         mBatchedLocationCallbackTransport.remove(callback);
 
@@ -2379,7 +2262,8 @@
      *
      * @return true if the command succeeds.
      */
-    public boolean sendExtraCommand(String provider, String command, Bundle extras) {
+    public boolean sendExtraCommand(
+            @NonNull String provider, @NonNull String command, @Nullable Bundle extras) {
         try {
             return mService.sendExtraCommand(provider, command, extras);
         } catch (RemoteException e) {
@@ -2448,7 +2332,7 @@
      * @hide
      */
     @SystemApi
-    public boolean isProviderPackage(String packageName) {
+    public boolean isProviderPackage(@NonNull String packageName) {
         try {
             return mService.isProviderPackage(packageName);
         } catch (RemoteException e) {
@@ -2464,7 +2348,7 @@
      */
     @SystemApi
     @RequiresPermission(Manifest.permission.LOCATION_HARDWARE)
-    public void setLocationControllerExtraPackage(String packageName) {
+    public void setLocationControllerExtraPackage(@NonNull String packageName) {
         try {
             mService.setLocationControllerExtraPackage(packageName);
         } catch (RemoteException e) {
diff --git a/location/java/android/location/LocationRequest.java b/location/java/android/location/LocationRequest.java
index 6fd063e..a05d850 100644
--- a/location/java/android/location/LocationRequest.java
+++ b/location/java/android/location/LocationRequest.java
@@ -17,6 +17,8 @@
 package android.location;
 
 import android.Manifest;
+import android.annotation.NonNull;
+import android.annotation.Nullable;
 import android.annotation.RequiresPermission;
 import android.annotation.SystemApi;
 import android.annotation.TestApi;
@@ -183,14 +185,16 @@
      *
      * @return a new location request
      */
+    @NonNull
     public static LocationRequest create() {
         return new LocationRequest();
     }
 
     /** @hide */
     @SystemApi
-    public static LocationRequest createFromDeprecatedProvider(String provider, long minTime,
-            float minDistance, boolean singleShot) {
+    @NonNull
+    public static LocationRequest createFromDeprecatedProvider(
+            @NonNull String provider, long minTime, float minDistance, boolean singleShot) {
         if (minTime < 0) minTime = 0;
         if (minDistance < 0) minDistance = 0;
 
@@ -215,8 +219,9 @@
 
     /** @hide */
     @SystemApi
-    public static LocationRequest createFromDeprecatedCriteria(Criteria criteria, long minTime,
-            float minDistance, boolean singleShot) {
+    @NonNull
+    public static LocationRequest createFromDeprecatedCriteria(
+            @NonNull Criteria criteria, long minTime, float minDistance, boolean singleShot) {
         if (minTime < 0) minTime = 0;
         if (minDistance < 0) minDistance = 0;
 
@@ -287,7 +292,7 @@
      * @return the same object, so that setters can be chained
      * @throws IllegalArgumentException if the quality constant is not valid
      */
-    public LocationRequest setQuality(int quality) {
+    public @NonNull LocationRequest setQuality(int quality) {
         checkQuality(quality);
         mQuality = quality;
         return this;
@@ -330,7 +335,7 @@
      * @return the same object, so that setters can be chained
      * @throws IllegalArgumentException if the interval is less than zero
      */
-    public LocationRequest setInterval(long millis) {
+    public @NonNull LocationRequest setInterval(long millis) {
         checkInterval(millis);
         mInterval = millis;
         if (!mExplicitFastestInterval) {
@@ -362,7 +367,7 @@
      * @hide
      */
     @SystemApi
-    public LocationRequest setLowPowerMode(boolean enabled) {
+    public @NonNull LocationRequest setLowPowerMode(boolean enabled) {
         mLowPowerMode = enabled;
         return this;
     }
@@ -386,7 +391,7 @@
      * @return the same object, so that setters can be chained
      */
     @RequiresPermission(Manifest.permission.WRITE_SECURE_SETTINGS)
-    public LocationRequest setLocationSettingsIgnored(boolean locationSettingsIgnored) {
+    public @NonNull LocationRequest setLocationSettingsIgnored(boolean locationSettingsIgnored) {
         mLocationSettingsIgnored = locationSettingsIgnored;
         return this;
     }
@@ -427,7 +432,7 @@
      * @return the same object, so that setters can be chained
      * @throws IllegalArgumentException if the interval is less than zero
      */
-    public LocationRequest setFastestInterval(long millis) {
+    public @NonNull LocationRequest setFastestInterval(long millis) {
         checkInterval(millis);
         mExplicitFastestInterval = true;
         mFastestInterval = millis;
@@ -463,7 +468,7 @@
      * @param millis duration of request in milliseconds
      * @return the same object, so that setters can be chained
      */
-    public LocationRequest setExpireIn(long millis) {
+    public @NonNull LocationRequest setExpireIn(long millis) {
         long elapsedRealtime = SystemClock.elapsedRealtime();
 
         // Check for > Long.MAX_VALUE overflow (elapsedRealtime > 0):
@@ -491,7 +496,7 @@
      * @param millis expiration time of request, in milliseconds since boot including suspend
      * @return the same object, so that setters can be chained
      */
-    public LocationRequest setExpireAt(long millis) {
+    public @NonNull LocationRequest setExpireAt(long millis) {
         mExpireAt = millis;
         if (mExpireAt < 0) mExpireAt = 0;
         return this;
@@ -522,7 +527,7 @@
      * @return the same object, so that setters can be chained
      * @throws IllegalArgumentException if numUpdates is 0 or less
      */
-    public LocationRequest setNumUpdates(int numUpdates) {
+    public @NonNull LocationRequest setNumUpdates(int numUpdates) {
         if (numUpdates <= 0) {
             throw new IllegalArgumentException(
                     "invalid numUpdates: " + numUpdates);
@@ -553,7 +558,8 @@
         }
     }
 
-    public LocationRequest setProvider(String provider) {
+    /** Sets the provider to use for this location request. */
+    public @NonNull LocationRequest setProvider(@NonNull String provider) {
         checkProvider(provider);
         mProvider = provider;
         return this;
@@ -561,13 +567,13 @@
 
     /** @hide */
     @SystemApi
-    public String getProvider() {
+    public @NonNull String getProvider() {
         return mProvider;
     }
 
     /** @hide */
     @SystemApi
-    public LocationRequest setSmallestDisplacement(float meters) {
+    public @NonNull LocationRequest setSmallestDisplacement(float meters) {
         checkDisplacement(meters);
         mSmallestDisplacement = meters;
         return this;
@@ -590,13 +596,13 @@
      * @hide
      */
     @SystemApi
-    public void setWorkSource(WorkSource workSource) {
+    public void setWorkSource(@Nullable WorkSource workSource) {
         mWorkSource = workSource;
     }
 
     /** @hide */
     @SystemApi
-    public WorkSource getWorkSource() {
+    public @Nullable WorkSource getWorkSource() {
         return mWorkSource;
     }