private void doPutRetryingIfNeeded() {
    do {
      if (!findAndSaveExistingEntry()) {
        return;
      }
      createNewEntryIfNeeded();
    } while (!addRegionEntryToMapAndDoPut());
  }
@return regionEntry if put completed, otherwise null.
geode-core/src/main/java/org/apache/geode/internal/cache/map/AbstractRegionMapPut.java