1 files changed, 12 insertions, 2 deletions
diff --git a/guava/src/com/google/common/collect/ImmutableSetMultimap.java b/guava/src/com/google/common/collect/ImmutableSetMultimap.java
index 4887ae79b..b1f8438cd 100644
--- a/guava/src/com/google/common/collect/ImmutableSetMultimap.java
+++ b/guava/src/com/google/common/collect/ImmutableSetMultimap.java
@@ -17,6 +17,7 @@
 package com.google.common.collect;
 
 import static com.google.common.base.Preconditions.checkNotNull;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.annotations.GwtIncompatible;
@@ -552,6 +553,15 @@ public class ImmutableSetMultimap<K, V> extends ImmutableMultimap<K, V>
     boolean isPartialView() {
       return false;
     }
+
+    // redeclare to help optimizers with b/310253115
+    @SuppressWarnings("RedundantOverride")
+    @Override
+    @J2ktIncompatible // serialization
+    @GwtIncompatible // serialization
+    Object writeReplace() {
+      return super.writeReplace();
+    }
   }
 
   private static <V> ImmutableSet<V> valueSet(
@@ -615,7 +625,7 @@ public class ImmutableSetMultimap<K, V> extends ImmutableMultimap<K, V>
     int tmpSize = 0;
 
     for (int i = 0; i < keyCount; i++) {
-      Object key = stream.readObject();
+      Object key = requireNonNull(stream.readObject());
       int valueCount = stream.readInt();
       if (valueCount <= 0) {
         throw new InvalidObjectException("Invalid value count " + valueCount);
@@ -623,7 +633,7 @@ public class ImmutableSetMultimap<K, V> extends ImmutableMultimap<K, V>
 
       ImmutableSet.Builder<Object> valuesBuilder = valuesBuilder(valueComparator);
       for (int j = 0; j < valueCount; j++) {
-        valuesBuilder.add(stream.readObject());
+        valuesBuilder.add(requireNonNull(stream.readObject()));
       }
       ImmutableSet<Object> valueSet = valuesBuilder.build();
       if (valueSet.size() != valueCount) {