Reverts third_party/protobuf: Update to HEAD (f52e188fe4)

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

 // Protocol Buffers - Google's data interchange format
 // Copyright 2008 Google Inc.  All rights reserved.
 // https://developers.google.com/protocol-buffers/
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 // notice, this list of conditions and the following disclaimer.
@@ skipping 39 matching lines @@
  * compiled before the new types were added.
  *
  * <p>Every {@link Message} contains an {@code UnknownFieldSet} (and every
  * {@link Message.Builder} contains an {@link Builder}).
  *
  * <p>Most users will never need to use this class.
  *
  * @author kenton@google.com Kenton Varda
  */
 public final class UnknownFieldSet implements MessageLite {
-
   private UnknownFieldSet() {}
 
   /** Create a new {@link Builder}. */
   public static Builder newBuilder() {
     return Builder.create();
   }
 
   /**
    * Create a new {@link Builder} and initialize it to be a copy
    * of {@code copyFrom}.
@@ skipping 53 matching lines @@
    */
   public Field getField(final int number) {
     final Field result = fields.get(number);
     return (result == null) ? Field.getDefaultInstance() : result;
   }
 
   /** Serializes the set and writes it to {@code output}. */
   @Override
   public void writeTo(final CodedOutputStream output) throws IOException {
     for (final Map.Entry<Integer, Field> entry : fields.entrySet()) {
-      Field field = entry.getValue();
-      field.writeTo(entry.getKey(), output);
+      entry.getValue().writeTo(entry.getKey(), output);
     }
   }
 
   /**
    * Converts the set to a string in protocol buffer text format. This is
    * just a trivial wrapper around
    * {@link TextFormat#printToString(UnknownFieldSet)}.
    */
   @Override
   public String toString() {
@@ skipping 869 matching lines @@
     @Override
     public UnknownFieldSet parsePartialFrom(
         CodedInputStream input, ExtensionRegistryLite extensionRegistry)
         throws InvalidProtocolBufferException {
       Builder builder = newBuilder();
       try {
         builder.mergeFrom(input);
       } catch (InvalidProtocolBufferException e) {
         throw e.setUnfinishedMessage(builder.buildPartial());
       } catch (IOException e) {
-        throw new InvalidProtocolBufferException(e)
+        throw new InvalidProtocolBufferException(e.getMessage())
             .setUnfinishedMessage(builder.buildPartial());
       }
       return builder.buildPartial();
     }
   }
 
   private static final Parser PARSER = new Parser();
   @Override
   public final Parser getParserForType() {
     return PARSER;
   }
 }