@org.apache.thrift.annotation.Nullable
    public static _Fields findByThriftId(int fieldId) {
      switch(fieldId) {
        case 1: // ROW
          return ROW;
        case 2: // COLUMNS
          return COLUMNS;
        case 3: // TIMESTAMP
          return TIMESTAMP;
        case 4: // TIME_RANGE
          return TIME_RANGE;
        case 5: // MAX_VERSIONS
          return MAX_VERSIONS;
        case 6: // FILTER_STRING
          return FILTER_STRING;
        case 7: // ATTRIBUTES
          return ATTRIBUTES;
        case 8: // AUTHORIZATIONS
          return AUTHORIZATIONS;
        case 9: // CONSISTENCY
          return CONSISTENCY;
        case 10: // TARGET_REPLICA_ID
          return TARGET_REPLICA_ID;
        case 11: // CACHE_BLOCKS
          return CACHE_BLOCKS;
        case 12: // STORE_LIMIT
          return STORE_LIMIT;
        case 13: // STORE_OFFSET
          return STORE_OFFSET;
        case 14: // EXISTENCE_ONLY
          return EXISTENCE_ONLY;
        case 15: // FILTER_BYTES
          return FILTER_BYTES;
        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/thrift2/generated/TGet.java