public static HFileBlockPair[] generateHFileBlocks(int blockSize, int numBlocks) {
    return generateBlocksForPath(blockSize, numBlocks, null);
  }
Just checks if heapsize grows when something is cached, and gets smaller when the same object
is evicted
hbase-server/src/test/java/org/apache/hadoop/hbase/io/hfile/CacheTestUtils.java