Enumeration generated from schema objects having allOf contain "null" prefix

[Hamza Ed-douibi]

When an enum is defined inside allOf, the generated UML enumeration contain the prefix null (e.g., nullStatus.

Definition example:

 "Sub": {
      "allOf": [
        {
          "$ref": "#/definitions/Base"
        },
        {
          "type": "object",
          "properties": {
            "status": {
              "type": "string",
              "enum": ["status1", "status2"]
            }
          }
        }
      ]
    }