public Builder setRegistrationDate(long value) {
            copyOnWrite();
            instance.setRegistrationDate(value);
            return this;
        }
<code>optional int64 registration_date = 6;</code>

@param value The registrationDate to set.
@return This builder for chaining.
turms-client-kotlin/src/main/java/im/turms/client/model/proto/model/user/UserInfo.java