Use J2ObjC's @RetainedWith annotation instead of @weak on ImmutableMa…

…p.keySet to prevent crashes on iOS.

TESTED=Created a map inside a autorelease pool and saved a reference to the
keyset. Checked that the keyset functions correctly outside the autorelease
pool. Checked that both the keyset and the map are deallocated by the
autorelease pool when not holding a reference to the keyset. Did this test with
both ImmutableMap.of(<2 entries>) and ImmutableBiMap.of(<2 entries>).

RELNOTES=J2ObjC: Fixes crashes from use of ImmutableMap.keySet().

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=233811320

android/guava/src/com/google/common/collect/ImmutableMap.java

@@ -25,6 +25,7 @@
 import com.google.common.annotations.GwtCompatible;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import com.google.errorprone.annotations.concurrent.LazyInit;
+import com.google.j2objc.annotations.RetainedWith;
 import com.google.j2objc.annotations.WeakOuter;
 import java.io.Serializable;
 import java.util.AbstractMap;
@@ -537,7 +538,7 @@ public ImmutableSet<Entry<K, V>> entrySet() {
 
   abstract ImmutableSet<Entry<K, V>> createEntrySet();
 
-  @LazyInit private transient ImmutableSet<K> keySet;
+  @LazyInit @RetainedWith private transient ImmutableSet<K> keySet;
 
   /**
    * Returns an immutable set of the keys in this map, in the same order that they appear in {@link

android/guava/src/com/google/common/collect/ImmutableMapKeySet.java

@@ -18,7 +18,6 @@
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.annotations.GwtIncompatible;
-import com.google.j2objc.annotations.Weak;
 import java.io.Serializable;
 import org.checkerframework.checker.nullness.compatqual.NullableDecl;
 
@@ -30,7 +29,7 @@
  */
 @GwtCompatible(emulated = true)
 final class ImmutableMapKeySet<K, V> extends IndexedImmutableSet<K> {
-  @Weak private final ImmutableMap<K, V> map;
+  private final ImmutableMap<K, V> map;
 
   ImmutableMapKeySet(ImmutableMap<K, V> map) {
     this.map = map;

guava/src/com/google/common/collect/ImmutableMap.java

@@ -26,6 +26,7 @@
 import com.google.common.annotations.VisibleForTesting;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import com.google.errorprone.annotations.concurrent.LazyInit;
+import com.google.j2objc.annotations.RetainedWith;
 import com.google.j2objc.annotations.WeakOuter;
 import java.io.Serializable;
 import java.util.AbstractMap;
@@ -718,7 +719,7 @@ public ImmutableSet<Entry<K, V>> entrySet() {
 
   abstract ImmutableSet<Entry<K, V>> createEntrySet();
 
-  @LazyInit private transient ImmutableSet<K> keySet;
+  @LazyInit @RetainedWith private transient ImmutableSet<K> keySet;
 
   /**
    * Returns an immutable set of the keys in this map, in the same order that they appear in {@link

guava/src/com/google/common/collect/ImmutableMapKeySet.java

@@ -20,7 +20,6 @@
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.annotations.GwtIncompatible;
-import com.google.j2objc.annotations.Weak;
 import java.io.Serializable;
 import java.util.Spliterator;
 import java.util.function.Consumer;
@@ -34,7 +33,7 @@
  */
 @GwtCompatible(emulated = true)
 final class ImmutableMapKeySet<K, V> extends IndexedImmutableSet<K> {
-  @Weak private final ImmutableMap<K, V> map;
+  private final ImmutableMap<K, V> map;
 
   ImmutableMapKeySet(ImmutableMap<K, V> map) {
     this.map = map;

guava/src/com/google/common/collect/RegularImmutableMap.java

@@ -209,7 +209,7 @@ ImmutableSet<K> createKeySet() {
 
   @GwtCompatible(emulated = true)
   private static final class KeySet<K, V> extends IndexedImmutableSet<K> {
-    @Weak private final RegularImmutableMap<K, V> map;
+    private final RegularImmutableMap<K, V> map;
 
     KeySet(RegularImmutableMap<K, V> map) {
       this.map = map;