Importing extended element features does not take effect

Developers
1

I want to extend the custom element inside the definitions element on the process, just like signal.
Here is my code:
1、First,I defined a json file。

{
  "name": "Ext",
  "uri": "http://ext.org/schema/1.0/bpmn",
  "prefix": "ext",
  "xml": {
    "tagAlias": "lowerCase"
  },

  "associations": [],


  "types": [

    {
      "name": "Shareniu",
      "superClass": [
        "RootElement"
      ],
      "properties": [
        {
          "name": "name",
          "isAttr": true,
          "type": "String"
        },
        {
          "name": "operations",
          "type": "Operation",
          "isMany": true
        },
        {
          "name": "implementationRef",
          "type": "String",
          "isAttr": true
        }
      ]
    },


    {
      "name": "ColoredShape",
      "extends": [ "bpmn:Process" ],
      "properties": [
        {
          "name": "stroke",
          "isAttr": true,
          "type": "String"
        },
        {
          "name": "fill",
          "isAttr": true,
          "type": "String"
        }
      ]
    },
    {
      "name": "Cc",
      "superClass": [ "Element" ],

      "meta": {
        "allowedIn": [ "*" ]
      },
      "properties": [
        {
          "name": "expression",
          "isAttr": true,
          "type": "String"
        },
        {
          "name": "class",
          "isAttr": true,
          "type": "String"
        },
        {
          "name": "delegateExpression",
          "isAttr": true,
          "type": "String"
        },
        {
          "name": "event",
          "isAttr": true,
          "type": "String"
        },
        {
          "name": "script",
          "type": "Script"
        },
        {
          "name": "fields",
          "type": "Field",
          "isMany": true
        }
      ]
    }

  ],
  "emumerations": [ ]
}

2、I used the following code to update the element properties.

  var _bpmnDefinitions  = bpmnModeler.get('elementRegistry').get('Process_1').businessObject.$parent;
                    var modeling = bpmnModeler.get('modeling');
                    console.log(modeling);

                    var    shareniuExtensionElements = elementHelper.createElement('ext:Cc', { event: 'start',
                        class: '111'}, _bpmnDefinitions, bpmnFactory);


                    _bpmnDefinitions.rootElements.push(shareniuExtensionElements);

3、After I exported the xml, he worked very well.

 <ext:cc class="111" event="start" />

4、When I import the xml generated above, the custom element is missing.（<ext:cc class=“111” event=“start” />）

2

Have you provided your moddle extension in the viewer, as in the example?