diff --git a/api/current.txt b/api/current.txt
index 2753085..c132efb 100755
--- a/api/current.txt
+++ b/api/current.txt
@@ -45696,6 +45696,7 @@
     method public java.util.Set<java.util.Map.Entry<K, V>> entrySet();
     method public V get(java.lang.Object);
     method public int indexOfKey(java.lang.Object);
+    method public int indexOfValue(java.lang.Object);
     method public boolean isEmpty();
     method public K keyAt(int);
     method public java.util.Set<K> keySet();
@@ -45716,6 +45717,7 @@
     ctor public ArraySet();
     ctor public ArraySet(int);
     ctor public ArraySet(android.util.ArraySet<E>);
+    ctor public ArraySet(java.util.Collection<? extends E>);
     method public boolean add(E);
     method public void addAll(android.util.ArraySet<? extends E>);
     method public boolean addAll(java.util.Collection<? extends E>);
@@ -46287,6 +46289,7 @@
     method public int keyAt(int);
     method public void put(int, boolean);
     method public void removeAt(int);
+    method public void setValueAt(int, boolean);
     method public int size();
     method public boolean valueAt(int);
   }
@@ -46305,6 +46308,7 @@
     method public int keyAt(int);
     method public void put(int, int);
     method public void removeAt(int);
+    method public void setValueAt(int, int);
     method public int size();
     method public int valueAt(int);
   }
diff --git a/core/java/android/util/ArrayMap.java b/core/java/android/util/ArrayMap.java
index 5108a79..294a179 100644
--- a/core/java/android/util/ArrayMap.java
+++ b/core/java/android/util/ArrayMap.java
@@ -71,19 +71,19 @@
     /**
      * Maximum number of entries to have in array caches.
      */
-    @UnsupportedAppUsage
+    @UnsupportedAppUsage(maxTargetSdk = 28) // Allocations are an implementation detail.
     private static final int CACHE_SIZE = 10;
 
     /**
      * Special hash array value that indicates the container is immutable.
      */
-    @UnsupportedAppUsage
+    @UnsupportedAppUsage(maxTargetSdk = 28) // Allocations are an implementation detail.
     static final int[] EMPTY_IMMUTABLE_INTS = new int[0];
 
     /**
      * @hide Special immutable empty ArrayMap.
      */
-    @UnsupportedAppUsage
+    @UnsupportedAppUsage(maxTargetSdk = 28) // Use your own singleton empty map.
     public static final ArrayMap EMPTY = new ArrayMap<>(-1);
 
     /**
@@ -92,21 +92,21 @@
      * The first entry in the array is a pointer to the next array in the
      * list; the second entry is a pointer to the int[] hash code array for it.
      */
-    @UnsupportedAppUsage
+    @UnsupportedAppUsage(maxTargetSdk = 28) // Allocations are an implementation detail.
     static Object[] mBaseCache;
-    @UnsupportedAppUsage
+    @UnsupportedAppUsage(maxTargetSdk = 28) // Allocations are an implementation detail.
     static int mBaseCacheSize;
-    @UnsupportedAppUsage
+    @UnsupportedAppUsage(maxTargetSdk = 28) // Allocations are an implementation detail.
     static Object[] mTwiceBaseCache;
-    @UnsupportedAppUsage
+    @UnsupportedAppUsage(maxTargetSdk = 28) // Allocations are an implementation detail.
     static int mTwiceBaseCacheSize;
 
     final boolean mIdentityHashCode;
-    @UnsupportedAppUsage
+    @UnsupportedAppUsage(maxTargetSdk = 28) // Hashes are an implementation detail. Use public key/value API.
     int[] mHashes;
-    @UnsupportedAppUsage
+    @UnsupportedAppUsage(maxTargetSdk = 28) // Storage is an implementation detail. Use public key/value API.
     Object[] mArray;
-    @UnsupportedAppUsage
+    @UnsupportedAppUsage(maxTargetSdk = 28) // Use size()
     int mSize;
     MapCollections<K, V> mCollections;
 
@@ -122,7 +122,7 @@
         }
     }
 
-    @UnsupportedAppUsage
+    @UnsupportedAppUsage(maxTargetSdk = 28) // Hashes are an implementation detail. Use indexOfKey(Object).
     int indexOf(Object key, int hash) {
         final int N = mSize;
 
@@ -161,7 +161,7 @@
         return ~end;
     }
 
-    @UnsupportedAppUsage
+    @UnsupportedAppUsage(maxTargetSdk = 28) // Use indexOf(null)
     int indexOfNull() {
         final int N = mSize;
 
@@ -200,7 +200,7 @@
         return ~end;
     }
 
-    @UnsupportedAppUsage
+    @UnsupportedAppUsage(maxTargetSdk = 28) // Allocations are an implementation detail.
     private void allocArrays(final int size) {
         if (mHashes == EMPTY_IMMUTABLE_INTS) {
             throw new UnsupportedOperationException("ArrayMap is immutable");
@@ -239,7 +239,7 @@
         mArray = new Object[size<<1];
     }
 
-    @UnsupportedAppUsage
+    @UnsupportedAppUsage(maxTargetSdk = 28) // Allocations are an implementation detail.
     private static void freeArrays(final int[] hashes, final Object[] array, final int size) {
         if (hashes.length == (BASE_SIZE*2)) {
             synchronized (ArrayMap.class) {
@@ -393,8 +393,15 @@
                 : indexOf(key, mIdentityHashCode ? System.identityHashCode(key) : key.hashCode());
     }
 
-    @UnsupportedAppUsage
-    int indexOfValue(Object value) {
+    /**
+     * Returns an index for which {@link #valueAt} would return the
+     * specified value, or a negative number if no keys map to the
+     * specified value.
+     * Beware that this is a linear search, unlike lookups by key,
+     * and that multiple keys can map to the same value and this will
+     * find only one of them.
+     */
+    public int indexOfValue(Object value) {
         final int N = mSize*2;
         final Object[] array = mArray;
         if (value == null) {
@@ -551,7 +558,7 @@
      * The array must already be large enough to contain the item.
      * @hide
      */
-    @UnsupportedAppUsage
+    @UnsupportedAppUsage(maxTargetSdk = 28) // Storage is an implementation detail. Use put(K, V).
     public void append(K key, V value) {
         int index = mSize;
         final int hash = key == null ? 0
diff --git a/core/java/android/util/ArraySet.java b/core/java/android/util/ArraySet.java
index 526a950..d74a0fe 100644
--- a/core/java/android/util/ArraySet.java
+++ b/core/java/android/util/ArraySet.java
@@ -71,15 +71,15 @@
     static int sTwiceBaseCacheSize;
 
     final boolean mIdentityHashCode;
-    @UnsupportedAppUsage
+    @UnsupportedAppUsage(maxTargetSdk = 28) // Hashes are an implementation detail. Use public API.
     int[] mHashes;
-    @UnsupportedAppUsage
+    @UnsupportedAppUsage(maxTargetSdk = 28) // Storage is an implementation detail. Use public API.
     Object[] mArray;
-    @UnsupportedAppUsage
+    @UnsupportedAppUsage(maxTargetSdk = 28) // Use size()
     int mSize;
     MapCollections<E, E> mCollections;
 
-    @UnsupportedAppUsage
+    @UnsupportedAppUsage(maxTargetSdk = 28) // Hashes are an implementation detail. Use indexOfKey(Object).
     private int indexOf(Object key, int hash) {
         final int N = mSize;
 
@@ -118,7 +118,7 @@
         return ~end;
     }
 
-    @UnsupportedAppUsage
+    @UnsupportedAppUsage(maxTargetSdk = 28) // Use indexOf(null)
     private int indexOfNull() {
         final int N = mSize;
 
@@ -157,7 +157,7 @@
         return ~end;
     }
 
-    @UnsupportedAppUsage
+    @UnsupportedAppUsage(maxTargetSdk = 28) // Allocations are an implementation detail.
     private void allocArrays(final int size) {
         if (size == (BASE_SIZE * 2)) {
             synchronized (ArraySet.class) {
@@ -215,7 +215,7 @@
         mArray = new Object[size];
     }
 
-    @UnsupportedAppUsage
+    @UnsupportedAppUsage(maxTargetSdk = 28) // Allocations are an implementation detail.
     private static void freeArrays(final int[] hashes, final Object[] array, final int size) {
         if (hashes.length == (BASE_SIZE * 2)) {
             synchronized (ArraySet.class) {
@@ -289,9 +289,10 @@
         }
     }
 
-    /** {@hide} */
-    @UnsupportedAppUsage
-    public ArraySet(Collection<E> set) {
+    /**
+     * Create a new ArraySet with items from the given collection.
+     */
+    public ArraySet(Collection<? extends E> set) {
         this();
         if (set != null) {
             addAll(set);
diff --git a/core/java/android/util/LongSparseLongArray.java b/core/java/android/util/LongSparseLongArray.java
index d5af922..af163ac 100644
--- a/core/java/android/util/LongSparseLongArray.java
+++ b/core/java/android/util/LongSparseLongArray.java
@@ -46,11 +46,11 @@
  * @hide
  */
 public class LongSparseLongArray implements Cloneable {
-    @UnsupportedAppUsage
+    @UnsupportedAppUsage(maxTargetSdk = 28) // The type isn't even public.
     private long[] mKeys;
-    @UnsupportedAppUsage
+    @UnsupportedAppUsage(maxTargetSdk = 28) // The type isn't even public.
     private long[] mValues;
-    @UnsupportedAppUsage
+    @UnsupportedAppUsage(maxTargetSdk = 28) // The type isn't even public.
     private int mSize;
 
     /**
diff --git a/core/java/android/util/SparseArray.java b/core/java/android/util/SparseArray.java
index aa5ca353..89ea2d3 100644
--- a/core/java/android/util/SparseArray.java
+++ b/core/java/android/util/SparseArray.java
@@ -56,11 +56,11 @@
     private static final Object DELETED = new Object();
     private boolean mGarbage = false;
 
-    @UnsupportedAppUsage
+    @UnsupportedAppUsage(maxTargetSdk = 28) // Use keyAt(int)
     private int[] mKeys;
-    @UnsupportedAppUsage
+    @UnsupportedAppUsage(maxTargetSdk = 28) // Use valueAt(int), setValueAt(int, E)
     private Object[] mValues;
-    @UnsupportedAppUsage
+    @UnsupportedAppUsage(maxTargetSdk = 28) // Use size()
     private int mSize;
 
     /**
diff --git a/core/java/android/util/SparseBooleanArray.java b/core/java/android/util/SparseBooleanArray.java
index 9c6b969..d4c4095 100644
--- a/core/java/android/util/SparseBooleanArray.java
+++ b/core/java/android/util/SparseBooleanArray.java
@@ -185,7 +185,9 @@
         return mValues[index];
     }
 
-    /** @hide */
+    /**
+     * Directly set the value at a particular index.
+     */
     public void setValueAt(int index, boolean value) {
         mValues[index] = value;
     }
@@ -304,10 +306,10 @@
         return buffer.toString();
     }
 
-    @UnsupportedAppUsage
+    @UnsupportedAppUsage(maxTargetSdk = 28) // Use keyAt(int)
     private int[] mKeys;
-    @UnsupportedAppUsage
+    @UnsupportedAppUsage(maxTargetSdk = 28) // Use valueAt(int), setValueAt(int, boolean)
     private boolean[] mValues;
-    @UnsupportedAppUsage
+    @UnsupportedAppUsage(maxTargetSdk = 28) // Use size()
     private int mSize;
 }
diff --git a/core/java/android/util/SparseIntArray.java b/core/java/android/util/SparseIntArray.java
index 1954753..9e6bad1 100644
--- a/core/java/android/util/SparseIntArray.java
+++ b/core/java/android/util/SparseIntArray.java
@@ -46,11 +46,11 @@
  * order in the case of <code>valueAt(int)</code>.</p>
  */
 public class SparseIntArray implements Cloneable {
-    @UnsupportedAppUsage
+    @UnsupportedAppUsage(maxTargetSdk = 28) // Use keyAt(int)
     private int[] mKeys;
-    @UnsupportedAppUsage
+    @UnsupportedAppUsage(maxTargetSdk = 28) // Use valueAt(int), setValueAt(int, int)
     private int[] mValues;
-    @UnsupportedAppUsage
+    @UnsupportedAppUsage(maxTargetSdk = 28) // Use size()
     private int mSize;
 
     /**
@@ -191,7 +191,6 @@
 
     /**
      * Directly set the value at a particular index.
-     * @hide
      */
     public void setValueAt(int index, int value) {
         mValues[index] = value;