public DataBlockEncoding getEffectiveDataBlockEncoding() {
      return this.reader.getEffectiveEncodingInCache(isCompaction);
    }
Scans blocks in the "scanned" section of the {@link HFile} until the next data block is
found.
@return the next block, or null if there are no more data blocks
hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/HFileReaderImpl.java