API Key credential:
https://swagger.io/docs/specification/v3_0/authentication/api-keys/
Credentials for HTTP Auth schemes:
https://www.iana.org/assignments/http-authschemes/http-auth-schemes.xhtml
OAuth2 credentials:
https://swagger.io/docs/specification/v3_0/authentication/oauth2/
Open ID Connect credentials:
https://swagger.io/docs/specification/v3_0/authentication/openid-connect-discovery/
Service Account credentials:
https://cloud.google.com/iam/docs/service-account-creds
API Key credential: