public Builder addBodies(org.box2d.proto.Box2D.PbBody value) {
        if (bodiesBuilder_ == null) {
          if (value == null) {
            throw new NullPointerException();
          }
          ensureBodiesIsMutable();
          bodies_.add(value);
          onChanged();
        } else {
          bodiesBuilder_.addMessage(value);
        }
        return this;
      }