1 files changed, 28 insertions, 0 deletions
diff --git a/guava/src/com/google/common/collect/ImmutableList.java b/guava/src/com/google/common/collect/ImmutableList.java
index 9c60caf3f..7c7801dbc 100644
--- a/guava/src/com/google/common/collect/ImmutableList.java
+++ b/guava/src/com/google/common/collect/ImmutableList.java
@@ -26,6 +26,7 @@ import static com.google.common.collect.RegularImmutableList.EMPTY;
 import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.GwtCompatible;
+import com.google.common.annotations.GwtIncompatible;
 import com.google.common.annotations.J2ktIncompatible;
 import com.google.common.annotations.VisibleForTesting;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
@@ -444,6 +445,12 @@ public abstract class ImmutableList<E> extends ImmutableCollection<E>
    * Returns an immutable list of the elements between the specified {@code fromIndex}, inclusive,
    * and {@code toIndex}, exclusive. (If {@code fromIndex} and {@code toIndex} are equal, the empty
    * immutable list is returned.)
+   *
+   * <p><b>Note:</b> in almost all circumstances, the returned {@link ImmutableList} retains a
+   * strong reference to {@code this}, which may prevent the original list from being garbage
+   * collected. If you want the original list to be eligible for garbage collection, you should
+   * create and use a copy of the sub list (e.g., {@code
+   * ImmutableList.copyOf(originalList.subList(...))}).
    */
   @Override
   public ImmutableList<E> subList(int fromIndex, int toIndex) {
@@ -498,6 +505,15 @@ public abstract class ImmutableList<E> extends ImmutableCollection<E>
     boolean isPartialView() {
       return true;
     }
+
+    // redeclare to help optimizers with b/310253115
+    @SuppressWarnings("RedundantOverride")
+    @Override
+    @J2ktIncompatible // serialization
+    @GwtIncompatible // serialization
+    Object writeReplace() {
+      return super.writeReplace();
+    }
   }
 
   /**
@@ -678,6 +694,15 @@ public abstract class ImmutableList<E> extends ImmutableCollection<E>
     boolean isPartialView() {
       return forwardList.isPartialView();
     }
+
+    // redeclare to help optimizers with b/310253115
+    @SuppressWarnings("RedundantOverride")
+    @Override
+    @J2ktIncompatible // serialization
+    @GwtIncompatible // serialization
+    Object writeReplace() {
+      return super.writeReplace();
+    }
   }
 
   @Override
@@ -724,6 +749,7 @@ public abstract class ImmutableList<E> extends ImmutableCollection<E>
 
   @Override
   @J2ktIncompatible // serialization
+  @GwtIncompatible // serialization
   Object writeReplace() {
     return new SerializedForm(toArray());
   }
@@ -901,4 +927,6 @@ public abstract class ImmutableList<E> extends ImmutableCollection<E>
       return asImmutableList(contents, size);
     }
   }
+
+  private static final long serialVersionUID = 0xcafebabe;
 }