public Map<DataBlockEncoding, Integer> getEncodingCountsForTest() {
    Map<DataBlockEncoding, Integer> counts = new EnumMap<>(DataBlockEncoding.class);
    for (LruCachedBlock block : map.values()) {
      DataBlockEncoding encoding = ((HFileBlock) block.getBuffer()).getDataBlockEncoding();
      Integer count = counts.get(encoding);
      counts.put(encoding, (count == null ? 0 : count) + 1);
    }
    return counts;
  }
Used in testing. May be very inefficient.
@return the set of cached file names
hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/LruBlockCache.java