@Override
  protected void standardSchemeWriteValue(org.apache.thrift.protocol.TProtocol oprot) throws org.apache.thrift.TException {
    switch (setField_) {
      case PUT:
        TPut put = (TPut)value_;
        put.write(oprot);
        return;
      case DELETE_SINGLE:
        TDelete deleteSingle = (TDelete)value_;
        deleteSingle.write(oprot);
        return;
      default:
        throw new java.lang.IllegalStateException("Cannot write union with unknown field " + setField_);
    }
  }
Find the _Fields constant that matches name, or null if its not found.
hbase-thrift/src/main/java/org/apache/hadoop/hbase/thrift2/generated/TMutation.java