Go client does not support vendor specific mime types

Created by: jimmidyson

Description

When using vendor specific mime types, e.g. application/vnd.my.custom.mime.type+json, the generated client does not correctly handling marshalling, even when the suffix specifies the underlying mime type to use (e.g. in this case json).

openapi-generator version

4.0.0-beta2

OpenAPI declaration file content or url

Command line used for generation

Language is go.

Steps to reproduce

Related issues/PRs

Suggest a fix/enhancement

Submitting a PR that fixes up the regexp in the client template used to check for JSON encoding.