public com.google.protobuf.ByteString
          getEmailBytes() {
        Object ref = email_;
        if (ref instanceof String) {
          com.google.protobuf.ByteString b =
              com.google.protobuf.ByteString.copyFromUtf8(
                  (String) ref);
          email_ = b;
          return b;
        } else {
          return (com.google.protobuf.ByteString) ref;
        }
      }
<code>optional string email = 3;</code>
@return The bytes for email.
core/src/test/java/com/alibaba/fastjson2/protobuf/PersonOuterClass.java