third_party/protobuf: Update to HEAD (83d681ee2c)

third_party/protobuf/java/core/src/main/java/com/google/protobuf/UnknownFieldSet.java

Index: third_party/protobuf/java/core/src/main/java/com/google/protobuf/UnknownFieldSet.java
diff --git a/third_party/protobuf/java/core/src/main/java/com/google/protobuf/UnknownFieldSet.java b/third_party/protobuf/java/core/src/main/java/com/google/protobuf/UnknownFieldSet.java
index c906420da1a6ea05bbd4f36b4880f84a2eec00e7..6d33d3a862f4b2bfc8667209139aebed603f3495 100644
--- a/third_party/protobuf/java/core/src/main/java/com/google/protobuf/UnknownFieldSet.java
+++ b/third_party/protobuf/java/core/src/main/java/com/google/protobuf/UnknownFieldSet.java
@@ -57,6 +57,7 @@ import java.util.TreeMap;
  * @author kenton@google.com Kenton Varda
  */
 public final class UnknownFieldSet implements MessageLite {
+
   private UnknownFieldSet() {}
 
   /** Create a new {@link Builder}. */
@@ -130,7 +131,8 @@ public final class UnknownFieldSet implements MessageLite {
   @Override
   public void writeTo(final CodedOutputStream output) throws IOException {
     for (final Map.Entry<Integer, Field> entry : fields.entrySet()) {
-      entry.getValue().writeTo(entry.getKey(), output);
+      Field field = entry.getValue();
+      field.writeTo(entry.getKey(), output);
     }
   }