@Override
  protected void checkType(_Fields setField, java.lang.Object value) throws java.lang.ClassCastException {
    switch (setField) {
      case PUT:
        if (value instanceof TPut) {
          break;
        }
        throw new java.lang.ClassCastException("Was expecting value of type TPut for field 'put', but got " + value.getClass().getSimpleName());
      case DELETE_SINGLE:
        if (value instanceof TDelete) {
          break;
        }
        throw new java.lang.ClassCastException("Was expecting value of type TDelete for field 'deleteSingle', but got " + value.getClass().getSimpleName());
      default:
        throw new java.lang.IllegalArgumentException("Unknown field id " + 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