code: public static void exports(Xml root, CollisionCategory category)
      {
          Check.notNull(root);
          Check.notNull(category);
  
          final Xml node = root.createChild(NODE_CATEGORY);
          node.writeString(ATT_NAME, category.getName());
          node.writeString(ATT_AXIS, category.getAxis().name());
          node.writeInteger(ATT_X, category.getOffsetX());
          node.writeInteger(ATT_Y, category.getOffsetY());
          node.writeBoolean(ATT_GLUE, category.isGlue());
  
          for (final CollisionGroup group : category.getGroups())
          {
              final Xml groupNode = node.createChild(TileGroupsConfig.NODE_GROUP);
              groupNode.setText(group.getName());
          }
      }
docs: Export the collision category data as a node.
  
  @param root The node root (must not be <code>null</code>).
  @param category The collision category to export (must not be <code>null</code>).
  @throws LionEngineException If error on writing.