@Override
  public MultiByteBuff moveBack(int length) {
    checkRefCount();
    while (length != 0) {
      if (length > curItem.position()) {
        length -= curItem.position();
        this.curItem.position(0);
        this.curItemIndex--;
        this.curItem = this.items[curItemIndex];
      } else {
        this.curItem.position(curItem.position() - length);
        break;
      }
    }
    return this;
  }
Jumps back the current position of this MBB by specified length.
hbase-common/src/main/java/org/apache/hadoop/hbase/nio/MultiByteBuff.java