@Override
  public ExtendedCell forceCopyOfBigCellInto(ExtendedCell cell) {
    int size = Segment.getCellLength(cell);
    Preconditions.checkArgument(size >= 0, "negative size");
    if (size + ChunkCreator.SIZEOF_CHUNK_HEADER <= dataChunkSize) {
      // Using copyCellInto for cells which are bigger than the original maxAlloc
      return copyCellInto(cell, dataChunkSize);
    } else {
      Chunk c = getNewExternalChunk(size);
      int allocOffset = c.alloc(size);
      return copyToChunkCell(cell, c.getData(), allocOffset, size);
    }
  }
When a cell's size is too big (bigger than maxAlloc), copyCellInto does not allocate it on
MSLAB. Since the process of flattening to CellChunkMap assumes that all cells are allocated on
MSLAB, during this process, the big cells are copied into MSLAB using this method.
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/MemStoreLABImpl.java