public Builder clear() {
        super.clear();
        categoryBits_ = 0;
        bitField0_ = (bitField0_ & ~0x00000001);
        maskBits_ = 0;
        bitField0_ = (bitField0_ & ~0x00000002);
        groupIndex_ = 0;
        bitField0_ = (bitField0_ & ~0x00000004);
        return this;
      }