code: private void restoreKeyGroupsInStateHandle()
  		throws IOException, StateMigrationException, RocksDBException {
  		try {
  			currentStateHandleInStream = currentKeyGroupsStateHandle.openInputStream();
  			cancelStreamRegistry.registerCloseable(currentStateHandleInStream);
  			currentStateHandleInView = new DataInputViewStreamWrapper(currentStateHandleInStream);
  			restoreKVStateMetaData();
  			restoreKVStateData();
  		} finally {
  			if (cancelStreamRegistry.unregisterCloseable(currentStateHandleInStream)) {
  				IOUtils.closeQuietly(currentStateHandleInStream);
  			}
  		}
  	}
docs: Restore one key groups state handle.