OpenAPI 3.1.0 support: bugs in useCircularStructures resolver option support

[char0n]

Some structures within OpenAPI 3.1.0 definition are falsely detected as circular structures. This can be seen on the following standard PetStore definition:

{
  "openapi": "3.1.0",
  "info": {
    "version": "1.0.0",
    "title": "Swagger Petstore",
    "license": {
      "name": "MIT"
    }
  },
  "servers": [
    {
      "url": "http://petstore.swagger.io/v1"
    }
  ],
  "paths": {
    "/pets": {
      "get": {
        "summary": "List all pets",
        "operationId": "listPets",
        "tags": [
          "pets"
        ],
        "parameters": [
          {
            "name": "limit",
            "in": "query",
            "description": "How many items to return at one time (max 100)",
            "required": false,
            "schema": {
              "type": "integer",
              "maximum": 100,
              "format": "int32"
            }
          }
        ],
        "responses": {
          "200": {
            "description": "A paged array of pets",
            "headers": {
              "x-next": {
                "description": "A link to the next page of responses",
                "schema": {
                  "type": "string"
                }
              }
            },
            "content": {
              "application/json": {
                "schema": {
                  "$ref": "#/components/schemas/Pets"
                }
              }
            }
          },
          "default": {
            "description": "unexpected error",
            "content": {
              "application/json": {
                "schema": {
                  "$ref": "#/components/schemas/Error"
                }
              }
            }
          }
        }
      },
      "post": {
        "summary": "Create a pet",
        "operationId": "createPets",
        "tags": [
          "pets"
        ],
        "responses": {
          "201": {
            "description": "Null response"
          },
          "default": {
            "description": "unexpected error",
            "content": {
              "application/json": {
                "schema": {
                  "$ref": "#/components/schemas/Error"
                }
              }
            }
          }
        }
      }
    },
    "/pets/{petId}": {
      "get": {
        "summary": "Info for a specific pet",
        "operationId": "showPetById",
        "tags": [
          "pets"
        ],
        "parameters": [
          {
            "name": "petId",
            "in": "path",
            "required": true,
            "description": "The id of the pet to retrieve",
            "schema": {
              "type": "string"
            }
          }
        ],
        "responses": {
          "200": {
            "description": "Expected response to a valid request",
            "content": {
              "application/json": {
                "schema": {
                  "$ref": "#/components/schemas/Pet"
                }
              }
            }
          },
          "default": {
            "description": "unexpected error",
            "content": {
              "application/json": {
                "schema": {
                  "$ref": "#/components/schemas/Error"
                }
              }
            }
          }
        }
      }
    }
  },
  "components": {
    "schemas": {
      "Pet": {
        "type": "object",
        "required": [
          "id",
          "name"
        ],
        "properties": {
          "id": {
            "type": "integer",
            "format": "int64"
          },
          "name": {
            "type": "string"
          },
          "tag": {
            "type": "string"
          }
        }
      },
      "Pets": {
        "type": "array",
        "maxItems": 100,
        "items": {
          "$ref": "#/components/schemas/Pet"
        }
      },
      "Error": {
        "type": "object",
        "required": [
          "code",
          "message"
        ],
        "properties": {
          "code": {
            "type": "integer",
            "format": "int32"
          },
          "message": {
            "type": "string"
          }
        }
      }
    }
  }
}

Dereferenced:

{
    "$$normalized": true,
    "components": {
      "schemas": {
        "Error": {
          "properties": {
            "code": {
              "format": "int32",
              "type": "integer",
            },
            "message": {
              "type": "string",
            },
          },
          "required": [
            "code",
            "message",
          ],
          "type": "object",
        },
        "Pet": {
          "properties": {
            "id": {
              "format": "int64",
              "type": "integer",
            },
            "name": {
              "type": "string",
            },
            "tag": {
              "type": "string",
            },
          },
          "required": [
            "id",
            "name",
          ],
          "type": "object",
        },
        "Pets": {
          "items": {
            "properties": {
              "id": {
                "format": "int64",
                "type": "integer",
              },
              "name": {
                "type": "string",
              },
              "tag": {
                "type": "string",
              },
            },
            "required": [
              "id",
              "name",
            ],
            "type": "object",
          },
          "maxItems": 100,
          "type": "array",
        },
      },
    },
    "info": {
      "license": {
        "name": "MIT",
      },
      "title": "Swagger Petstore",
      "version": "1.0.0",
    },
    "openapi": "3.1.0",
    "paths": {
      "/pets": {
        "get": {
          "operationId": "listPets",
          "parameters": [
            {
              "description": "How many items to return at one time (max 100)",
              "in": "query",
              "name": "limit",
              "required": false,
              "schema": {
                "format": "int32",
                "maximum": 100,
                "type": "integer",
              },
            },
          ],
          "responses": {
            "200": {
              "content": {
                "application/json": {
                  "schema": {
                    "items": {
                      "properties": {
                        "id": {
                          "format": "int64",
                          "type": "integer",
                        },
                        "name": {
                          "type": "string",
                        },
                        "tag": {
                          "type": "string",
                        },
                      },
                      "required": [
                        "id",
                        "name",
                      ],
                      "type": "object",
                    },
                    "maxItems": 100,
                    "type": "array",
                  },
                },
              },
              "description": "A paged array of pets",
              "headers": {
                "x-next": {
                  "description": "A link to the next page of responses",
                  "schema": {
                    "type": "string",
                  },
                },
              },
            },
            "default": {
              "content": {
                "application/json": {
                  "schema": {
                    "properties": {
                      "code": {
                        "format": "int32",
                        "type": "integer",
                      },
                      "message": {
                        "type": "string",
                      },
                    },
                    "required": [
                      "code",
                      "message",
                    ],
                    "type": "object",
                  },
                },
              },
              "description": "unexpected error",
            },
          },
          "servers": [
            {
              "url": "http://petstore.swagger.io/v1",
            },
          ],
          "summary": "List all pets",
          "tags": [
            "pets",
          ],
        },
        "post": {
          "operationId": "createPets",
          "responses": {
            "201": {
              "description": "Null response",
            },
            "default": {
              "content": {
                "application/json": {
                  "schema": {
                    "$ref": "https://example.com/petstore.json#/components/schemas/Error",
                  },
                },
              },
              "description": "unexpected error",
            },
          },
          "servers": [
            {
              "url": "http://petstore.swagger.io/v1",
            },
          ],
          "summary": "Create a pet",
          "tags": [
            "pets",
          ],
        },
        "servers": [
          {
            "url": "http://petstore.swagger.io/v1",
          },
        ],
      },
      "/pets/{petId}": {
        "get": {
          "operationId": "showPetById",
          "parameters": [
            {
              "description": "The id of the pet to retrieve",
              "in": "path",
              "name": "petId",
              "required": true,
              "schema": {
                "type": "string",
              },
            },
          ],
          "responses": {
            "200": {
              "content": {
                "application/json": {
                  "schema": {
                    "$ref": "https://example.com/petstore.json#/components/schemas/Pet",
                  },
                },
              },
              "description": "Expected response to a valid request",
            },
            "default": {
              "content": {
                "application/json": {
                  "schema": {
                    "$ref": "https://example.com/petstore.json#/components/schemas/Error",
                  },
                },
              },
              "description": "unexpected error",
            },
          },
          "servers": [
            {
              "url": "http://petstore.swagger.io/v1",
            },
          ],
          "summary": "Info for a specific pet",
          "tags": [
            "pets",
          ],
        },
        "servers": [
          {
            "url": "http://petstore.swagger.io/v1",
          },
        ],
      },
    },
    "servers": [
      {
        "url": "http://petstore.swagger.io/v1",
      },
    ],
  },
}

It is apparent from dereferenced definitions that some references remained unresolved (like https://example.com/petstore.json#/components/schemas/Pet) even though the definition contains no circular structures.