Copy element with custom attributes

I have a schema

{
  "name": Some-name",
  "uri": "http://some-company.com/schema/1.0/bpmn",
  "prefix": "custom",
  "xml": {
    "tagAlias": "lowerCase"
  },
  "types": {
     {
      "name": "DataObject",
      "extends": ["bpmn:DataObject"],
      "properties": [
        {
          "name": "businessObjectDefinitionCode",
          "isAttr": true,
          "type": "String"
        },
        {
          "name": "businessObjectKeyVariableName",
          "isAttr": true,
          "type": "String"
        }
      ]
    },
  }
}

“extends: [bpmn:DataObject]” - works correctly

 <bpmn:dataObjectReference id="DataObjectReference_0ar087y" name="SomeDataObjectReferenceName " dataObjectRef="DataObject_10pl1sf"/>
 <bpmn:dataObject id="DataObject_10pl1sf" custom:businessObjectDefinitionCode="Documet_OutBox_" custom:businessObjectKeyVariableName="VAR1"/>

If I copy and paste an element using the “CTRL+C/CTRL+V” hotkeys, the custom attributes for the bpmn:dataObject element are not copied.