OpenID Connect support (#865)

* Added OpenID Connect support

Utilized Spring Security's OAuth2 respectively OIDC support as another
possibility to manage users and their permissions.

Signed-off-by: Brandon Schmitt <Brandon.Schmitt@kiwigrid.com>

* Document OpenID Connect Support

Signed-off-by: Brandon Schmitt <Brandon.Schmitt@kiwigrid.com>

* Updated license in OidcUserManagementAutoConfiguration.java

Signed-off-by: Brandon Schmitt <Brandon.Schmitt@kiwigrid.com>

* Revert updated license notice and add Kiwigrid license file

This reverts commit 23d36245

Signed-off-by: Brandon Schmitt <Brandon.Schmitt@kiwigrid.com>

* Resolve SonarQube issues

- Explicitly import the needed specific classes
- Document public methods
- Add `static` to the constant `JwtAuthoritiesOidcUserService.INVALID_REQUEST`
- Remove superfluous runtime exception `OAuth2AuthenticationException`

Signed-off-by: Brandon Schmitt <Brandon.Schmitt@kiwigrid.com>

* Add OidcUser support in SpringSecurityAuditorAware

Signed-off-by: Brandon Schmitt <Brandon.Schmitt@kiwigrid.com>

* Secure Management API using OpenID Connect, too.

Signed-off-by: Brandon Schmitt <Brandon.Schmitt@kiwigrid.com>

hawkbit-security-core/src/main/java/org/eclipse/hawkbit/security/SpringSecurityAuditorAware.java

@@ -14,6 +14,7 @@ import org.springframework.data.domain.AuditorAware;
 import org.springframework.security.core.Authentication;
 import org.springframework.security.core.context.SecurityContextHolder;
 import org.springframework.security.core.userdetails.UserDetails;
+import org.springframework.security.oauth2.core.oidc.user.OidcUser;
 
 /**
  * Auditor class that allows BaseEntitys to insert current logged in user for
@@ -38,6 +39,9 @@ public class SpringSecurityAuditorAware implements AuditorAware<String> {
         if (authentication.getPrincipal() instanceof UserDetails) {
             return ((UserDetails) authentication.getPrincipal()).getUsername();
         }
+        if (authentication.getPrincipal() instanceof OidcUser) {
+            return ((OidcUser) authentication.getPrincipal()).getPreferredUsername();
+        }
         return authentication.getPrincipal().toString();
     }