code: static KeyRange keyRangeSingleRow(byte[] rowKey) {
          KeyRange keyRange = new KeyRange();
          keyRange.setStart_key(rowKey);
          keyRange.setEnd_key(rowKey);
          keyRange.setCount(1);
          return keyRange;
      }
docs: Create a KeyRange that selects a single row with the given key.
  
  @param rowKey    Row key as a byte[].
  @return          KeyRange that starts and ends with the given key.