private synchronized CompletableFuture<AppendResult> append0(MetaKeyValue kv) {
        return innerStream.append(new DefaultRecordBatch(1, System.currentTimeMillis(), Collections.emptyMap(), MetaKeyValue.encode(kv)));
    }
Append a batch of meta key values without trims.

@return a future of append result
core/src/main/scala/kafka/log/streamaspect/MetaStream.java