private void maybeResolveAwaitingChunk() {
    PutChunk resolutionAwaitingChunk = getChunkInState(ChunkState.AwaitingBlobTypeResolution);
    if (resolutionAwaitingChunk != null) {
      resolutionAwaitingChunk.onFillComplete(true);
      if (resolutionAwaitingChunk.isReady()) {
        routerCallback.onPollReady();
      }
    }
  }
Prepare the awaiting chunks to be sent to server.
Note that there can be only one awaiting chunk, and that chunk will always be the first data chunk of a blob.
ambry-router/src/main/java/com/github/ambry/router/PutOperation.java