public boolean isReusable() {
    return isReusable;
  }
If offHeapData is set then ignore the "data" and "validLength" fields. The offHeapData field is
unretained so it can only be used while the RegionEntry is still synced. When done with the
offHeapData, null it out if you want to reuse the byte[] later.
geode-core/src/main/java/org/apache/geode/internal/cache/BytesAndBitsForCompactor.java