From dd7ccd3784e6743676ab525fabeb0d554e93d59e Mon Sep 17 00:00:00 2001
From: Chaoren Lin <aoe@google.com>
Date: Mon, 20 Apr 2026 13:36:30 -0700
Subject: [PATCH] Make some methods in `AbstractMapBasedMultimap` abstract
 since they are overridden in all subclasses.

RELNOTES=n/a
PiperOrigin-RevId: 902799974
---
 .../common/collect/AbstractMapBasedMultimap.java      | 11 +++--------
 .../common/collect/AbstractMapBasedMultimap.java      | 11 +++--------
 2 files changed, 6 insertions(+), 16 deletions(-)

diff --git a/android/guava/src/com/google/common/collect/AbstractMapBasedMultimap.java b/android/guava/src/com/google/common/collect/AbstractMapBasedMultimap.java
index 78b4f0275d5a..5363e844da2e 100644
--- a/android/guava/src/com/google/common/collect/AbstractMapBasedMultimap.java
+++ b/android/guava/src/com/google/common/collect/AbstractMapBasedMultimap.java
@@ -32,7 +32,6 @@
 import java.io.Serializable;
 import java.util.AbstractCollection;
 import java.util.Collection;
-import java.util.Collections;
 import java.util.Comparator;
 import java.util.ConcurrentModificationException;
 import java.util.Iterator;
@@ -265,10 +264,8 @@ public Collection<V> removeAll(@Nullable Object key) {
     return unmodifiableCollectionSubclass(output);
   }
 
-  <E extends @Nullable Object> Collection<E> unmodifiableCollectionSubclass(
-      Collection<E> collection) {
-    return Collections.unmodifiableCollection(collection);
-  }
+  abstract <E extends @Nullable Object> Collection<E> unmodifiableCollectionSubclass(
+      Collection<E> collection);
 
   @Override
   public void clear() {
@@ -300,9 +297,7 @@ public Collection<V> get(@ParametricNullness K key) {
    * Generates a decorated collection that remains consistent with the values in the multimap for
    * the provided key. Changes to the multimap may alter the returned collection, and vice versa.
    */
-  Collection<V> wrapCollection(@ParametricNullness K key, Collection<V> collection) {
-    return new WrappedCollection(key, collection, null);
-  }
+  abstract Collection<V> wrapCollection(@ParametricNullness K key, Collection<V> collection);
 
   final List<V> wrapList(
       @ParametricNullness K key, List<V> list, @Nullable WrappedCollection ancestor) {
diff --git a/guava/src/com/google/common/collect/AbstractMapBasedMultimap.java b/guava/src/com/google/common/collect/AbstractMapBasedMultimap.java
index ca9969397c80..b320950c9ab2 100644
--- a/guava/src/com/google/common/collect/AbstractMapBasedMultimap.java
+++ b/guava/src/com/google/common/collect/AbstractMapBasedMultimap.java
@@ -32,7 +32,6 @@
 import java.io.Serializable;
 import java.util.AbstractCollection;
 import java.util.Collection;
-import java.util.Collections;
 import java.util.Comparator;
 import java.util.ConcurrentModificationException;
 import java.util.Iterator;
@@ -267,10 +266,8 @@ public Collection<V> removeAll(@Nullable Object key) {
     return unmodifiableCollectionSubclass(output);
   }
 
-  <E extends @Nullable Object> Collection<E> unmodifiableCollectionSubclass(
-      Collection<E> collection) {
-    return Collections.unmodifiableCollection(collection);
-  }
+  abstract <E extends @Nullable Object> Collection<E> unmodifiableCollectionSubclass(
+      Collection<E> collection);
 
   @Override
   public void clear() {
@@ -302,9 +299,7 @@ public Collection<V> get(@ParametricNullness K key) {
    * Generates a decorated collection that remains consistent with the values in the multimap for
    * the provided key. Changes to the multimap may alter the returned collection, and vice versa.
    */
-  Collection<V> wrapCollection(@ParametricNullness K key, Collection<V> collection) {
-    return new WrappedCollection(key, collection, null);
-  }
+  abstract Collection<V> wrapCollection(@ParametricNullness K key, Collection<V> collection);
 
   final List<V> wrapList(
       @ParametricNullness K key, List<V> list, @Nullable WrappedCollection ancestor) {