[BUG][JAVA] import mapping of alias types in API interface

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• Have you tested with the latest master to confirm the issue still exists?
• Have you searched for related issues/PRs?
• What's the actual output vs expected output?
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Description

when using importMapping for alias types, the generated code does not use the importmapping in the api interface

Expected

    @POST
    @Path("/{id}")
    Response typeAliasIdPost(@PathParam("id") foo.bar.TypeAlias id);

Actual

    @POST
    @Path("/{id}")
    Response typeAliasIdPost(@PathParam("id") String id);

openapi-generator version

5.0.0

OpenAPI declaration file content or url

https://gist.github.com/PhilippParis/28c40d590b4a9019cb8040b143e09884

Generation Details

<generatorName>jaxrs-spec</generatorName>
<interfaceOnly>true</interfaceOnly>
 <java8>true</java8>
<importMappings>
    <importMapping>TypeAlias=foo.bar.TypeAlias</importMapping>
</importMappings>

Steps to reproduce

run openapi-generator 5.0.0 with specified generation details

Related issues/PRs

https://github.com/OpenAPITools/openapi-generator/issues/3589

Use the linked OpenAPI declaration and the listed jaxrs-spec generation settings to reproduce the generated API interface. Compare the alias parameter with the expected foo.bar.TypeAlias import mapping; done means the interface uses the mapped alias type instead of String.