[BUG] setApiKeyToObject & setBearerAuthToObject functions set header to undefined

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?
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• What's the actual output vs expected output?
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Description

When the apiKey and accessToken config settings are functions, setApiKeyToObject, setBearerAuthToObject , etc... will set the header values to undefined or empty string if the config function returns either.

openapi-generator version

6.0.1

Suggest a fix

The setApiKeyToObject, setBearerAuthToObject, etc... functions need to check if the localVarApiKeyValue, accessToken, etc... local variable is undefined; if so, then do not add the key to the object. When the apiKey and accessToken config settings are a function and there is multiple possible authentication schemes for a rest api(api key, bearer, etc...), we need to be able to tell the setApiKeyToObject, setBearerAuthToObject , etc... functions that we do not want to add the header to the request object.

Start in modules/openapi-generator/src/main/resources/typescript-axios/common.mustache, at setApiKeyToObject, setBearerAuthToObject, and the related authentication helpers. Check how localVarApiKeyValue and accessToken are handled when configuration functions return undefined or an empty string. Done means those values no longer add corresponding headers to the request object.