suspicious behavior when checking ContentType

[AdrienDevillers]

I'm currently setting up pact testing in my scala project with grpc and protobuf using pact4s

I had to modify a bit pact4s to be able to generate a V4Pact compatible with plugins,
when running the test Suite I get an error 415 Unsuported Media type

the line causing trouble is line 239 in mock_server.rs
Ok(content_type) => if content_type.base_type().to_string().starts_with("application/grpc")

I feel like the base_type function is not working properly, from what I understand it is replacing sub_type by suffix
and in my case I have the following contentType: "application/grpc+proto", the method base_type() will then transform it to "application/proto" which then fails the condition and returns an error 415,

I modified the plugin so that it only checks the sub-type and it worked.

am I missing something?