public void clear() {
        restorableEntries.clear();
        flushedEntries.clear();
        flushedRemovals.clear();
    }
Remove all {@link #flushedEntryStored(Object) flushed entries}, {@link #flushedEntryRemoved(Object) flushed removals},
streams/src/test/java/org/apache/kafka/streams/state/KeyValueStoreTestDriver.java