code: public static boolean has(Xml root, String group)
      {
          Check.notNull(root);
          Check.notNull(group);
  
          for (final Xml node : root.getChildren(NODE_COLLISION))
          {
              if (node.readString(ATT_GROUP).equals(group))
              {
                  return true;
              }
          }
          return false;
      }
docs: Check if node has group node.
  
  @param root The root node (must not be <code>null</code>).
  @param group The group name to check (must not be <code>null</code>).
  @return <code>true</code> if has group, <code>false</code> else.
  @throws LionEngineException If invalid argument.