[BUG] extension refs are not supported

[seanlaff]

Description

The generator ignores OpenAPI extension references ( https://github.com/OAI/OpenAPI-Specification/blob/master/versions/2.0.md#patterned-objects ) because this conditional has whitelist of references

openapi-generator/modules/openapi-generator/src/main/java/org/openapitools/codegen/utils/ModelUtils.java

Lines 279 to 287 in 046db19

	public static String getSimpleRef(String ref) {
	if (ref.startsWith("#/components/")) {
	ref = ref.substring(ref.lastIndexOf("/") + 1);
	} else if (ref.startsWith("#/definitions/")) {
	ref = ref.substring(ref.lastIndexOf("/") + 1);
	} else {
	LOGGER.warn("Failed to get the schema name: {}", ref);
	//throw new RuntimeException("Failed to get the schema: " + ref);
	return null;

I'm using the GRPC-gateway to generate openAPI spec for my gRPC apis, and it uses OpenAPI extensions to hold references to the stream response (See this PR grpc-ecosystem/grpc-gateway#850 ) This generator puts x-stream-definitions refs at the root of the openAPI spec. Which gives these warnings

[main] WARN  o.o.codegen.utils.ModelUtils - #/x-stream-definitions/aggregationListAggregationsResponse is not defined
[main] WARN  o.o.codegen.utils.ModelUtils - Failed to get the schema name: #/x-stream-definitions/aggregationListAggregationsResponse

openapi-generator version

4.0.0

OpenAPI declaration file content or url

https://gist.github.com/seanlaff/9a8d88027bd775b5ef31e63abf3fb946

Command line used for generation

docker run --rm -v ${PWD}:/local openapitools/openapi-generator-cli:v4.0.0-beta generate \
    -i /local/test.json \
    -g typescript-axios \
    -o /local/out/ts

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[seanlaff]

I realize this is not simple as adding another check for #/x- in the getSimpleRef() function because that function takes the shortened string and passes it to funcitons like getParameter, getApiResponse, etc. For example:

openapi-generator/modules/openapi-generator/src/main/java/org/openapitools/codegen/utils/ModelUtils.java

Lines 669 to 678 in 046db19

	public static Parameter getParameter(OpenAPI openAPI, String name) {
	if (name == null) {
	return null;
	}
	if (openAPI != null && openAPI.getComponents() != null && openAPI.getComponents().getParameters() != null) {
	return openAPI.getComponents().getParameters().get(name);
	}
	return null;
	}

Whats the best way to go about supporting this behavior/ should it be supported?

[loganknecht]

+1 on this. I really wish I could use references 😭

[adamdecaf]

Is there a hint for how I could fix this and issue a PR? I'm unable to generate a client due to this bug and I'd like to offer a fix. I see ModelUtils doesn't attempt to resolve remote references, but is that already done elsewhere in the codebase?