@Override
  public void removePhase1(InternalRegion region, boolean clear) throws RegionClearedException {
    synchronized (this) {
      Helper.removeFromDisk(this, region, clear);
      _removePhase1();
    }
  }
Abstract implementation class of RegionEntry interface. This is adds Disk support behavior

@since GemFire 3.5.1
geode-core/src/main/java/org/apache/geode/internal/cache/entries/AbstractOplogDiskRegionEntry.java