@Override
  public void serializeToWAL(IWALByteBufferView buffer) {
    memChunk.serializeToWAL(buffer);
  }
Check whether this MemChunkGroup contains a measurement. If a VECTOR_PLACEHOLDER passed from
outer, always return true because AlignedMemChunkGroup existing.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/storageengine/dataregion/memtable/AlignedWritableMemChunkGroup.java