{
  "name": "verify-form-submit-required",
  "nodes": [
    {"id": "n1", "name": "Form", "type": "form-trigger", "position": {"x": 0, "y": 0},
     "config": {"title": "Upload",
                "fields": [{"name": "image", "label": "Image", "type": "file", "required": true}]}}
  ],
  "connections": [],
  "http": {
    "method": "POST",
    "path": "/webhook/{workflowId}",
    "multipart": {"fields": {"_probe": "x"}, "files": {}},
    "expectStatus": 400,
    "expectBodyContains": ["Image", "required"]
  }
}