public Builder mergeLocalAnchorB(org.box2d.proto.Box2D.PbVec2 value) {
        if (localAnchorBBuilder_ == null) {
          if (((bitField0_ & 0x00000040) == 0x00000040) &&
              localAnchorB_ != org.box2d.proto.Box2D.PbVec2.getDefaultInstance()) {
            localAnchorB_ =
              org.box2d.proto.Box2D.PbVec2.newBuilder(localAnchorB_).mergeFrom(value).buildPartial();
          } else {
            localAnchorB_ = value;
          }
          onChanged();
        } else {
          localAnchorBBuilder_.mergeFrom(value);
        }
        bitField0_ |= 0x00000040;
        return this;
      }