public Builder setPoints(
          int index, org.box2d.proto.Box2D.PbVec2.Builder builderForValue) {
        if (pointsBuilder_ == null) {
          ensurePointsIsMutable();
          points_.set(index, builderForValue.build());
          onChanged();
        } else {
          pointsBuilder_.setMessage(index, builderForValue.build());
        }
        return this;
      }