code: public boolean isSet(_Fields field) {
      if (field == null) {
        throw new IllegalArgumentException();
      }
  
      switch (field) {
      case IS_EMPTY:
        return isSetIs_empty();
      case BOOL_VAL:
        return isSetBool_val();
      case INT_VAL:
        return isSetInt_val();
      case LONG_VAL:
        return isSetLong_val();
      case FLOAT_VAL:
        return isSetFloat_val();
      case DOUBLE_VAL:
        return isSetDouble_val();
      case BINARY_VAL:
        return isSetBinary_val();
      case TYPE:
        return isSetType();
      }
      throw new IllegalStateException();
    }
docs: Returns true if field corresponding to fieldID is set (has been assigned a value) and false otherwise