Expose systemReady for SystemServer

SystemServer cannot call the hidden API of ConnectivityManager
after it becomes a part of mainline module. So expose the hidden
API for SystemServer.

Bug: 182963354
Test: m services
Change-Id: I9c1dc8eb1401dbdc069d5c9fc3992f4c7939b70e
diff --git a/framework/api/module-lib-current.txt b/framework/api/module-lib-current.txt
index c3b1800..05e0813 100644
--- a/framework/api/module-lib-current.txt
+++ b/framework/api/module-lib-current.txt
@@ -12,6 +12,7 @@
     method @RequiresPermission(anyOf={android.net.NetworkStack.PERMISSION_MAINLINE_NETWORK_STACK, android.Manifest.permission.NETWORK_SETTINGS}) public void registerSystemDefaultNetworkCallback(@NonNull android.net.ConnectivityManager.NetworkCallback, @NonNull android.os.Handler);
     method @RequiresPermission(anyOf={android.Manifest.permission.NETWORK_SETTINGS, android.Manifest.permission.NETWORK_STACK, android.net.NetworkStack.PERMISSION_MAINLINE_NETWORK_STACK}) public void requestBackgroundNetwork(@NonNull android.net.NetworkRequest, @NonNull android.os.Handler, @NonNull android.net.ConnectivityManager.NetworkCallback);
     method @RequiresPermission(anyOf={android.Manifest.permission.MANAGE_TEST_NETWORKS, android.Manifest.permission.NETWORK_STACK}) public void simulateDataStall(int, long, @NonNull android.net.Network, @NonNull android.os.PersistableBundle);
+    method public void systemReady();
     field public static final String PRIVATE_DNS_MODE_OFF = "off";
     field public static final String PRIVATE_DNS_MODE_OPPORTUNISTIC = "opportunistic";
     field public static final String PRIVATE_DNS_MODE_PROVIDER_HOSTNAME = "hostname";
diff --git a/framework/src/android/net/ConnectivityManager.java b/framework/src/android/net/ConnectivityManager.java
index 8b66928..dc06cd9 100644
--- a/framework/src/android/net/ConnectivityManager.java
+++ b/framework/src/android/net/ConnectivityManager.java
@@ -915,8 +915,8 @@
 
     /**
      * @hide
-     * TODO: Expose for SystemServer when becomes a module.
      */
+    @SystemApi(client = MODULE_LIBRARIES)
     public void systemReady() {
         try {
             mService.systemReady();