@org.apache.thrift.annotation.Nullable
    public static _Fields findByThriftId(int fieldId) {
      switch(fieldId) {
        case 1: // USERNAME
          return USERNAME;
        case 2: // SCOPE
          return SCOPE;
        case 4: // ACTIONS
          return ACTIONS;
        case 5: // TABLE_NAME
          return TABLE_NAME;
        case 6: // NS_NAME
          return NS_NAME;
        default:
          return null;
      }
    }
Find the _Fields constant that matches fieldId, or null if its not found.
hbase-thrift/src/main/java/org/apache/hadoop/hbase/thrift/generated/TAccessControlEntity.java