With the following plugin that enters a custom unordered list with both UL and LI having class names:

CKEDITOR.plugins.add( 'mylist', {
    icons: 'mylist',
    init: function( editor ) {
        editor.addCommand( 'mylistCommand', { 
            exec : function( editor ) {
                editor.insertHtml('<ul class="mylist"><li class="myitem">&nbsp;</li></ul>');
            }
        });
        editor.ui.addButton( 'My List', {
            label: 'Insert My List',
            command: 'mylistCommand',
            toolbar: 'insert'
        });
    }
});

Everything works fine but when I type some text into the first bullet, then hit ENTER twice to get out off list item mode and create a new P tag, the P tag inherits the class="myitem". For example:

<ul class="mylist">
	<li class="myitem">test</li>
</ul>

<p class="myitem">&nbsp;</p>

Is there a way to stop that?