[BUG] [Java] Cross-path references are not properly considered for Parameters

Description

When parsing the Parameters section from an operation, cross-path reference parameters are ignored. This is not consistent with other elements which are properly included in the final OpenAPI object.

openapi-generator version

Version 7.7.0

OpenAPI declaration file content or url

"/attribute/{namespace}":
    delete:
      description: |
        Delete an attribute namespace and all attributes below.

        This operation is the same as the one defined with [DELETE /attribute/{namespace}/_meta](#/Attributes/delete_attribute__namespace___meta).
      parameters:
        - $ref: "#/paths/~1attribute~1%7Bnamespace%7D/get/parameters/0"
 

Full spec file is here: https://github.com/APIs-guru/openapi-directory/blob/main/APIs/opensuse.org/obs/2.10.50/openapi.yaml

Generation Details

Use the following code:

        OpenAPIParser openAPIV3Parser = new OpenAPIParser();
        ParseOptions options = new ParseOptions();
        options.setResolve(true);
        options.setFlatten(true);

        OpenAPI openAPI = openAPIV3Parser.readContents(Files.readString(Paths.get("openapi.yaml")), null, options).getOpenAPI();
        PathItem pathItem = openAPI.getPaths().get("/attribute/{namespace}");

You can then check the Parameters list of the DELETE operation is empty instead of having one parameter.

Steps to reproduce

See above

Suggest a fix

The issue seems to be this code from the io.swagger.v3.parser.processors.ParameterProcessor class:

    if (parameter.get$ref().startsWith("#") && parameter.get$ref().indexOf("#/components/parameters") <= -1) {
                    //TODO: Not possible to add warning during resolve doesn't accept result as an input. Hence commented below line.
                    //result.warning(location, "The parameter should use Reference Object to link to parameters that are defined at the OpenAPI Object's components/parameters.");
                    continue;
                }

Which only includes refs that are from the components section. One possible fix is that it should just include parameters that are referencing other paths 'as is' rather than trying to solve it.

Start with io.swagger.v3.parser.processors.ParameterProcessor and reproduce the issue using the referenced openapi.yaml, OpenAPIParser, and ParseOptions configuration. Inspect why the DELETE operation's PathItem parameters omit the cross-path reference, then verify that the resolved Parameters list contains the referenced parameter without regressing component parameter references.