public Builder setBodies(
          int index, org.box2d.proto.Box2D.PbBody.Builder builderForValue) {
        if (bodiesBuilder_ == null) {
          ensureBodiesIsMutable();
          bodies_.set(index, builderForValue.build());
          onChanged();
        } else {
          bodiesBuilder_.setMessage(index, builderForValue.build());
        }
        return this;
      }