generator-jhipster: SecurityUtils .getCurrentUserLogin in a microservice returns "null" with OAuth2 and Okta

Overview of the issue

Calling SecurityUtils.getCurrentUserLogin() in a microservice returns null instead of the user login

Motivation for or Use Case

It should be possible to retrieve the user from the security context

Reproduce the error

Use SecurityUtils.getCurrentUserLogin() in a microservice using Okta for the authentication

Related issues

#9613

Suggest a Fix

} else if (authentication instanceof JwtAuthenticationToken) {
    return (String) ((JwtAuthenticationToken)authentication).getToken().getClaims().get("preferred_username");
} else if (authentication.getPrincipal() instanceof DefaultOidcUser) {

preferred_username doesn’t exist when using Okta, is it specific to Keycloak?

JHipster Version(s)

store@0.0.0 /Users/theo/Documents/perso/oauth2/store
└── generator-jhipster@6.5.1

JDL for the Entity configuration(s) entityName.json files generated in the .jhipster directory

application {
  config {
    baseName gateway,
    packageName com.jhipster.gateway,
    applicationType gateway,
    authenticationType oauth2,
    prodDatabaseType postgresql,
    serviceDiscoveryType eureka
  }
  entities Product
}

application {
  config {
    baseName store,
    packageName com.jhipster.store,
    applicationType microservice,
    authenticationType oauth2,
    prodDatabaseType postgresql,
    serviceDiscoveryType eureka
    serverPort 8081
  }
  entities Product
}

entity Product {
  title String
}

microservice Product with store

Environment and Tools

openjdk version “11.0.4” 2019-07-16 OpenJDK Runtime Environment AdoptOpenJDK (build 11.0.4+11) OpenJDK 64-Bit Server VM AdoptOpenJDK (build 11.0.4+11, mixed mode)

git version 2.23.0

node: v10.17.0

npm: 6.11.3

yeoman: 3.1.1

Docker version 19.03.5, build 633a0ea

docker-compose version 1.24.1, build 4667896b

Browsers and Operating System

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