public void incNumOverflowBytesOnDisk(long delta) {
    if (delta == 0) {
      return;
    }
    numOverflowBytesOnDisk.addAndGet(delta);
    // The following could be reenabled at a future time.
    // I deadcoded for now to make sure I didn't have it break
    // the last 6.5 regression.
    // It is possible that numOverflowBytesOnDisk might go negative
    // for a short period of time if a decrement ever happens before
    // its corresponding increment.
    // if (res < 0) {
    // throw new IllegalStateException("numOverflowBytesOnDisk < 0 " + res);
    // }
  }
Increments the current number of entries whose value has been overflowed to disk by this
bucket, by a given amount.
geode-core/src/main/java/org/apache/geode/internal/cache/BucketRegion.java