private byte[] generateTmpBytes(int length) {
    StringBuilder result = new StringBuilder();
    while (result.length() < length) {
      result.append("-");
    }
    return Bytes.toBytes(result.substring(0, length));
  }
A ByteBuffAllocator that rewrite the bytebuffers right after released. It can be used for test
whether there are prematurely releasing backing bytebuffers.
hbase-common/src/main/java/org/apache/hadoop/hbase/io/DeallocateRewriteByteBuffAllocator.java