Broken ModelConverterContextImpl resolve method for hierarchical data structure

[Birthright50]

I used latest swagger 2.1.2, spring doc 1.3.1 and spring boot mvc 2.2.6.

I have a method that returns data in a hierarchical structure:

@GetMapping(Routes.Item.External.VIEWS_STRUCTURE)
 public List<ViewStructureShared> getViewStructure(@Validated GetViewStructureRequest request) {
     return itemsService.getViewStructure(request.getViewName(), request.getLang());
}

ViewStructureShared model:

public class ViewStructureShared {
    private long id;
    private long viewId;
    private List<ViewStructureShared> children;
    private String title;
    private Long categoryId;
    private Long tagId;
    private short order;
    private boolean global;
}

Swagger generates right response for this endpoint:

        "responses": {
          "200": {
            "description": "default response",
            "content": {
              "*/*": {
                "schema": {
                  "type": "array",
                  "items": {
                    "$ref": "#/components/schemas/ViewStructureShared"
                  }
                }
              }
            }
          }
        }
...
      "ViewStructureShared": {
        "type": "object",
        "properties": {
          "id": {
            "type": "integer",
            "format": "int64"
          },
          "viewId": {
            "type": "integer",
            "format": "int64"
          },
          "children": {
            "type": "array",
            "items": {
              "$ref": "#/components/schemas/ViewStructureShared"
            }
          },
          "title": {
            "type": "string"
          },
          "categoryId": {
            "type": "integer",
            "format": "int64"
          },
          "tagId": {
            "type": "integer",
            "format": "int64"
          },
          "order": {
            "type": "integer",
            "format": "int32"
          },
          "global": {
            "type": "boolean"
          }
        }
      }

But, if response wrapper appears, then everything changes.

    @GetMapping(Routes.Item.External.VIEWS_STRUCTURE)
    public ActionResult<List<ViewStructureShared>> getViewStructure(@Validated GetViewStructureRequest request) {
        return ActionResult.ok(itemsService.getViewStructure(request.getViewName(), request.getLang()));
    }

ActionResult response wrapper structure:

public class ActionResult<T> {

    protected T value;
    protected boolean success;
    protected String errorCode;
    protected String message;
}

then swagger generates this schema model:

      "ViewStructureShared": {
        "type": "object",
        "properties": {
          "id": {
            "type": "integer",
            "format": "int64"
          },
          "viewId": {
            "type": "integer",
            "format": "int64"
          },
          "title": {
            "type": "string"
          },
          "categoryId": {
            "type": "integer",
            "format": "int64"
          },
          "tagId": {
            "type": "integer",
            "format": "int64"
          },
          "order": {
            "type": "integer",
            "format": "int32"
          },
          "global": {
            "type": "boolean"
          }
        }
      }

no more children field in schema.

Why is everything fine in the first case, but everything breaks in the second? I tried to figure it out.

The problem is here.

    public Schema resolve(AnnotatedType type) {
        if (processedTypes.contains(type)) {
            return modelByType.get(type);
        } else {
            processedTypes.add(type);
        }

In first case we have two different annotated types (by AnnotatedType.getType() method):
sun.reflect.generics.reflectiveObjects.ParameterizedTypeImpl for returned object in controller and com.fasterxml.jackson.databind.type.CollectionType for List<ViewStructureShared> in ViewStructureShared.

But in second we have both identical (by equals method) com.fasterxml.jackson.databind.type.CollectionType,
therefore, this code omits this processing and no children anymore, as I understand it, this is done to protect against recursion. But specifically, this example should work.

There is one hack that will help children - specify a different type of collection, for example Collection instead of List:

    @GetMapping(Routes.Item.External.VIEWS_STRUCTURE)
    public ActionResult<Collection<ViewStructureShared>> getViewStructure(@Validated GetViewStructureRequest request) {
        return ActionResult.ok(itemsService.getViewStructure(request.getViewName(), request.getLang()));
    }

but this is not the right decision

[webron]

See #3511.