@Override
  public String toString() {
    return this.getClass().getSimpleName() + "[pos=" + position() + ", lim=" + limit() + ", cap= "
      + capacity() + "]";
  }
Read long which was written to fitInBytes bytes and increment position.
@param fitInBytes In how many bytes given long is stored.
@return The value of parsed long.
hbase-common/src/main/java/org/apache/hadoop/hbase/nio/ByteBuff.java