docs: public static int bytesToId(final byte[] row_key) {
      if (row_key.length < TREE_ID_WIDTH) {
        throw new IllegalArgumentException("Row key was less than " + 
            TREE_ID_WIDTH + " in length");
      }
      
      final byte[] tree_id = new byte[INT_WIDTH];
      System.arraycopy(row_key, 0, tree_id, INT_WIDTH - Tree.TREE_ID_WIDTH(), 
          Tree.TREE_ID_WIDTH());
      return Bytes.getInt(tree_id);    
    }