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Read the contribution guidelines.
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Preliminary openIdConnect support

This is a (somewhat simplistic) approach to include some openIdConnect support into openapi-generator. As openIdConnect is simply a specialization of OAuth2 [1], I extented CodegenSecurity to include the isOpenIdConnect field. If this field is set to true, isOAuth is also set true.

Openid retrieves most information from openIdConnectUrl [2]. The JSON available at this URL is specified by the discovery protocol [3]. In the new Class OpenIdConnect, I retrieve the information and construct CodegenSecurity objects from it. This means that the openIdConnect discovery stuff is mainly consumed as OAuth2 flows (that are already handled by openapi-generator).

This should be enough to fix #4406 and similiar bugs were the fix is simply to treat openIdConnect as some sort of OAuth2.

Certainly this solution could be extended (later) for more openIdConnect specific stuff.

[1] https://blog.runscope.com/posts/understanding-oauth-2-and-openid-connect [2] https://swagger.io/docs/specification/authentication/openid-connect-discovery/ [3] https://openid.net/specs/openid-connect-discovery-1_0.html