[protoc-gen-openapiv2] Incorrectly generated OpenAPIv2 spec when using repeated_path_param_separator option

[Raiden1974]

🐛 Bug Report

When I use repeated_path_param_separator option with any value I get result in my documentation where "collectionFormat": "multi". I found what in template.go you force set 'multi' to "collectionFormat".

[johanbrandhorst]

Hi, thanks for your bug report! It does indeed seem like the value set at https://github.com/grpc-ecosystem/grpc-gateway/blame/a6c12767cc494e67993e933ff4a501d667606d83/protoc-gen-openapiv2/internal/genopenapi/template.go#L1214C41-L1214C41 is overridden at https://github.com/grpc-ecosystem/grpc-gateway/blame/a6c12767cc494e67993e933ff4a501d667606d83/protoc-gen-openapiv2/internal/genopenapi/template.go#L333. I'm not sure exactly what the best fix is here, but I expect the command line flag should take precedence. Would you be willing to contribute a fix to this?

[Raiden1974]

As I understand it, the same situation is in the gateway code generator