public Builder mergeFrom(
          com.google.protobuf.CodedInputStream input,
          com.google.protobuf.ExtensionRegistryLite extensionRegistry)
          throws java.io.IOException {
        com.google.protobuf.UnknownFieldSet.Builder unknownFields =
          com.google.protobuf.UnknownFieldSet.newBuilder(
            this.getUnknownFields());
        while (true) {
          int tag = input.readTag();
          switch (tag) {
            case 0:
              this.setUnknownFields(unknownFields.build());
              onChanged();
              return this;
            default: {
              if (!parseUnknownField(input, unknownFields,
                                     extensionRegistry, tag)) {
                this.setUnknownFields(unknownFields.build());
                onChanged();
                return this;
              }
              break;
            }
            case 8: {
              bitField0_ |= 0x00000001;
              tag_ = input.readInt64();
              break;
            }
            case 21: {
              bitField0_ |= 0x00000002;
              restitution_ = input.readFloat();
              break;
            }
            case 29: {
              bitField0_ |= 0x00000004;
              friction_ = input.readFloat();
              break;
            }
            case 37: {
              bitField0_ |= 0x00000008;
              density_ = input.readFloat();
              break;
            }
            case 40: {
              bitField0_ |= 0x00000010;
              sensor_ = input.readBool();
              break;
            }
            case 82: {
              org.box2d.proto.Box2D.PbFilter.Builder subBuilder = org.box2d.proto.Box2D.PbFilter.newBuilder();
              if (hasFilter()) {
                subBuilder.mergeFrom(getFilter());
              }
              input.readMessage(subBuilder, extensionRegistry);
              setFilter(subBuilder.buildPartial());
              break;
            }
            case 90: {
              org.box2d.proto.Box2D.PbShape.Builder subBuilder = org.box2d.proto.Box2D.PbShape.newBuilder();
              if (hasShape()) {
                subBuilder.mergeFrom(getShape());
              }
              input.readMessage(subBuilder, extensionRegistry);
              setShape(subBuilder.buildPartial());
              break;
            }
          }
        }
      }