public org.box2d.proto.Box2D.PbFixture buildPartial() {
        org.box2d.proto.Box2D.PbFixture result = new org.box2d.proto.Box2D.PbFixture(this);
        int from_bitField0_ = bitField0_;
        int to_bitField0_ = 0;
        if (((from_bitField0_ & 0x00000001) == 0x00000001)) {
          to_bitField0_ |= 0x00000001;
        }
        result.tag_ = tag_;
        if (((from_bitField0_ & 0x00000002) == 0x00000002)) {
          to_bitField0_ |= 0x00000002;
        }
        result.restitution_ = restitution_;
        if (((from_bitField0_ & 0x00000004) == 0x00000004)) {
          to_bitField0_ |= 0x00000004;
        }
        result.friction_ = friction_;
        if (((from_bitField0_ & 0x00000008) == 0x00000008)) {
          to_bitField0_ |= 0x00000008;
        }
        result.density_ = density_;
        if (((from_bitField0_ & 0x00000010) == 0x00000010)) {
          to_bitField0_ |= 0x00000010;
        }
        result.sensor_ = sensor_;
        if (((from_bitField0_ & 0x00000020) == 0x00000020)) {
          to_bitField0_ |= 0x00000020;
        }
        if (filterBuilder_ == null) {
          result.filter_ = filter_;
        } else {
          result.filter_ = filterBuilder_.build();
        }
        if (((from_bitField0_ & 0x00000040) == 0x00000040)) {
          to_bitField0_ |= 0x00000040;
        }
        if (shapeBuilder_ == null) {
          result.shape_ = shape_;
        } else {
          result.shape_ = shapeBuilder_.build();
        }
        result.bitField0_ = to_bitField0_;
        onBuilt();
        return result;
      }