public Builder clearId() {
        bitField0_ = (bitField0_ & ~0x00000002);
        id_ = 0;
        onChanged();
        return this;
      }
<code>optional int32 id = 2;</code>
@return This builder for chaining.
core/src/test/java/com/alibaba/fastjson2/protobuf/PersonOuterClass.java