public boolean isSet(_Fields field) {
    if (field == null) {
      throw new java.lang.IllegalArgumentException();
    }

    switch (field) {
    case AINT:
      return isSetAint();
    case A_STRING:
      return isSetAString();
    case LINT:
      return isSetLint();
    case L_STRING:
      return isSetLString();
    case LINT_STRING:
      return isSetLintString();
    case M_STRING_STRING:
      return isSetMStringString();
    case ATTRIBUTES:
      return isSetAttributes();
    case UNION_FIELD1:
      return isSetUnionField1();
    case UNION_FIELD2:
      return isSetUnionField2();
    case UNION_FIELD3:
      return isSetUnionField3();
    }
    throw new java.lang.IllegalStateException();
  }
Returns true if field corresponding to fieldID is set (has been assigned a value) and false otherwise
serde/src/gen/thrift/gen-javabean/org/apache/hadoop/hive/serde2/thrift/test/Complex.java