public DataBlockEncoder getEncoder() {
    if (encoder == null && id != 0) {
      // lazily create the encoder
      encoder = createEncoder(encoderCls);
    }
    return encoder;
  }
Return new data block encoder for given algorithm type.
@return data block encoder if algorithm is specified, null if none is selected.
hbase-common/src/main/java/org/apache/hadoop/hbase/io/encoding/DataBlockEncoding.java