Fix docs for PendingIntent.getBroadcast() and annotate as nullable

Fixes: 277630907
Test: docs only
Relnote: PendingIntent.getBroadcast() is now correctly marked @nullable
Change-Id: Ifff965b38abb4fccc4709a52a5a71d6372a388a5

Author: alanv

core/core/api/current.ignore

@@ -0,0 +1,3 @@
+// Baseline format: 1.0
+InvalidNullConversion: androidx.core.app.PendingIntentCompat#getBroadcast(android.content.Context, int, android.content.Intent, int, boolean):
+    Attempted to change method return from @NonNull to @Nullable: incompatible change for method androidx.core.app.PendingIntentCompat.getBroadcast(android.content.Context,int,android.content.Intent,int,boolean)

core/core/api/current.txt

@@ -866,7 +866,7 @@ package androidx.core.app {
     method public static android.app.PendingIntent getActivities(android.content.Context, int, android.content.Intent![], int, boolean);
     method public static android.app.PendingIntent getActivity(android.content.Context, int, android.content.Intent, int, boolean);
     method public static android.app.PendingIntent getActivity(android.content.Context, int, android.content.Intent, int, android.os.Bundle, boolean);
-    method public static android.app.PendingIntent getBroadcast(android.content.Context, int, android.content.Intent, int, boolean);
+    method public static android.app.PendingIntent? getBroadcast(android.content.Context, int, android.content.Intent, int, boolean);
     method @RequiresApi(26) public static android.app.PendingIntent getForegroundService(android.content.Context, int, android.content.Intent, int, boolean);
     method public static android.app.PendingIntent getService(android.content.Context, int, android.content.Intent, int, boolean);
   }

core/core/api/public_plus_experimental_current.txt

@@ -866,7 +866,7 @@ package androidx.core.app {
     method public static android.app.PendingIntent getActivities(android.content.Context, int, android.content.Intent![], int, boolean);
     method public static android.app.PendingIntent getActivity(android.content.Context, int, android.content.Intent, int, boolean);
     method public static android.app.PendingIntent getActivity(android.content.Context, int, android.content.Intent, int, android.os.Bundle, boolean);
-    method public static android.app.PendingIntent getBroadcast(android.content.Context, int, android.content.Intent, int, boolean);
+    method public static android.app.PendingIntent? getBroadcast(android.content.Context, int, android.content.Intent, int, boolean);
     method @RequiresApi(26) public static android.app.PendingIntent getForegroundService(android.content.Context, int, android.content.Intent, int, boolean);
     method public static android.app.PendingIntent getService(android.content.Context, int, android.content.Intent, int, boolean);
   }

core/core/api/restricted_current.ignore

@@ -0,0 +1,3 @@
+// Baseline format: 1.0
+InvalidNullConversion: androidx.core.app.PendingIntentCompat#getBroadcast(android.content.Context, int, android.content.Intent, int, boolean):
+    Attempted to change method return from @NonNull to @Nullable: incompatible change for method androidx.core.app.PendingIntentCompat.getBroadcast(android.content.Context,int,android.content.Intent,int,boolean)

core/core/api/restricted_current.txt

@@ -963,7 +963,7 @@ package androidx.core.app {
     method public static android.app.PendingIntent getActivities(android.content.Context, int, android.content.Intent![], int, boolean);
     method public static android.app.PendingIntent getActivity(android.content.Context, int, android.content.Intent, int, boolean);
     method public static android.app.PendingIntent getActivity(android.content.Context, int, android.content.Intent, int, android.os.Bundle, boolean);
-    method public static android.app.PendingIntent getBroadcast(android.content.Context, int, android.content.Intent, int, boolean);
+    method public static android.app.PendingIntent? getBroadcast(android.content.Context, int, android.content.Intent, int, boolean);
     method @RequiresApi(26) public static android.app.PendingIntent getForegroundService(android.content.Context, int, android.content.Intent, int, boolean);
     method public static android.app.PendingIntent getService(android.content.Context, int, android.content.Intent, int, boolean);
   }

core/core/src/main/java/androidx/core/app/PendingIntentCompat.java

@@ -29,6 +29,7 @@
 import androidx.annotation.DoNotInline;
 import androidx.annotation.IntDef;
 import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
 import androidx.annotation.RequiresApi;
 import androidx.annotation.RestrictTo;
 
@@ -135,10 +136,13 @@ public final class PendingIntentCompat {
     /**
      * Retrieves a {@link PendingIntent} with mandatory mutability flag set on supported platform
      * versions. The caller provides the flag as combination of all the other values except
-     * mutability flag. This method combines mutability flag when necessary. See {@link
-     * PendingIntent#getBroadcast(Context, int, Intent, int)}.
+     * mutability flag. This method combines mutability flag when necessary.
+     *
+     * @return Returns an existing or new PendingIntent matching the given parameters. May return
+     *         {@code null} only if {@link PendingIntent#FLAG_NO_CREATE} has been supplied.
+     * @see PendingIntent#getBroadcast(Context, int, Intent, int)
      */
-    public static @NonNull PendingIntent getBroadcast(
+    public static @Nullable PendingIntent getBroadcast(
             @NonNull Context context,
             int requestCode,
             @NonNull Intent intent,