public static <TNode extends AvlNode> TNode getFirst(TNode root) {
      if (root != null) {
        while (root.avlLeft != null) {
          root = (TNode) root.avlLeft;
        }
      }
      return root;
    }
Return the first node of the tree.
@param root the current root of the tree
@return the first (min) node of the tree
hbase-common/src/main/java/org/apache/hadoop/hbase/util/AvlUtil.java