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

    switch (field) {
    case NAME:
      return isSetName();
    case CONFIGURATION:
      return isSetConfiguration();
    }
    throw new IllegalStateException();
  }
Returns true if field corresponding to fieldID is set (has been assigned a value) and false otherwise
hbase-thrift/src/main/java/org/apache/hadoop/hbase/thrift2/generated/NamespaceDescriptor.java