Support for @JsonView on @ExceptionHandler methods

[Malkeekalsi]

Currently, springdoc-api ignores the @JsonView annotation on exception handler methods, and it generates a generic schema(all fields) for the ResponseBean. However, spring rest supports @JsonView annotation on exception handler methods and generates a different schema for different Views of ResponseBean.

This PR introduces the support for @JsonView annotation on Exception handler methods.

In the below example, exception handlers for INTERNAL_SERVER_ERROR and BAD_REQUEST have different JsonViews, but springdoc generates the same schema /components/schemas/FooBean for both error responses.

public class FooBean {
    @JsonView(Views.View2.class)
    private String message;
    @JsonView(Views.View1.class)
    private int code;
}

//Exception handler class
@ControllerAdvice(assignableTypes = HelloController.class)
public class FooErrorHandler {

	@ExceptionHandler
	@ResponseStatus(value = HttpStatus.INTERNAL_SERVER_ERROR)
	@JsonView(Views.View1.class)
	public ResponseEntity<FooBean> storeAssignmentPublishingError(Exception e) {
		return new ResponseEntity<>(new FooBean("INTERNAL_SERVER_ERROR",500), HttpStatus.INTERNAL_SERVER_ERROR);
	}

	@ExceptionHandler
	@ResponseStatus(value = HttpStatus.BAD_REQUEST)
	@JsonView(Views.View2.class)
	public ResponseEntity<FooBean> storeAssignmentPublishingError(CustomException e) {
		return new ResponseEntity<>(new FooBean("BAD Request",400), HttpStatus.BAD_REQUEST);
	}
}

//Existing response. Documentation is not generated as per @JsonView annotation

 "responses":{
               "500":{
                  "description":"Internal Server Error",
                  "content":{
                     "*/*":{
                        "schema":{
                           "$ref":"#/components/schemas/FooBean"
                        }
                     }
                  }
               },
               "400":{
                  "description":"Bad Request",
                  "content":{
                     "*/*":{
                        "schema":{
                           "$ref":"#/components/schemas/FooBean"
                        }
                     }
                  }
               },
               "200":{
                  "description":"OK",
                  "content":{
                     "*/*":{
                        "schema":{
                           "type":"string"
                        }
                     }
                  }
               }
            },
       "components":{
         "schemas":{
                 "FooBean":{
                    "type":"object",
                    "properties":{
                       "message":{
                          "type":"string"
                       },
                       "code":{
                          "type":"integer",
                          "format":"int32"
                       }
                    }
                 }
              }
          }

//After this PR
In the below example, springdoc generates the different schema (#/components/schemas/FooBean_View1 , #/components/schemas/FooBean_View2) for error responses.

 "responses":{
          "500":{
            "description":"Internal Server Error",
            "content":{
              "*/*":{
                "schema":{
                  "$ref":"#/components/schemas/FooBean_View1"
                }
              }
            }
          },
          "400":{
            "description":"Bad Request",
            "content":{
              "*/*":{
                "schema":{
                  "$ref":"#/components/schemas/FooBean_View2"
                }
              }
            }
          },
          "200":{
            "description":"OK",
            "content":{
              "*/*":{
                "schema":{
                  "type":"string"
                }
              }
            }
          }
        },
       "components":{
          "schemas":{
            "FooBean_View1":{
              "type":"object",
              "properties":{
                "code":{
                  "type":"integer",
                  "format":"int32"
                }
              }
            },
            "FooBean_View2":{
              "type":"object",
              "properties":{
                "message":{
                  "type":"string"
                },
                "code":{
                  "type":"integer",
                  "format":"int32"
                }
              }
            }
          }
        }

[bnasslahsen]

Thank you @Malkeekalsi for your contribution