@Override
  public void get(int sourceOffset, byte[] dst, int offset, int length) {
    checkRefCount();
    int itemIndex = getItemIndex(sourceOffset);
    ByteBuffer item = this.items[itemIndex];
    sourceOffset = sourceOffset - this.itemBeginPos[itemIndex];
    while (length > 0) {
      int toRead = Math.min((item.limit() - sourceOffset), length);
      ByteBufferUtils.copyFromBufferToArray(dst, item, sourceOffset, offset, toRead);
      length -= toRead;
      if (length == 0) break;
      itemIndex++;
      item = this.items[itemIndex];
      offset += toRead;
      sourceOffset = 0;
    }
  }
Copies the specified number of bytes from this MBB's current position to the byte[]'s offset.
Also advances the position of the MBB by the given length.
hbase-common/src/main/java/org/apache/hadoop/hbase/nio/MultiByteBuff.java