@Override
  public byte getByteAfterPosition(int offset) {
    checkRefCount();
    // Mostly the index specified will land within this current item. Short circuit for that
    int index = offset + this.position();
    int itemIndex = getItemIndexFromCurItemIndex(index);
    return ByteBufferUtils.toByte(this.items[itemIndex], index - this.itemBeginPos[itemIndex]);
  }
Fetches the byte at the given index. Does not change position of the underlying ByteBuffers
@return the byte at the given index
hbase-common/src/main/java/org/apache/hadoop/hbase/nio/MultiByteBuff.java