Issues/300: Remove useless null check

Author: François

api/src/main/java/io/kafbat/ui/service/rbac/extractor/OauthAuthorityExtractor.java

@@ -59,8 +59,8 @@ private Set<String> extractUsernameRoles(AccessControlService acs, DefaultOAuth2
             .filter(s -> s.getProvider().equals(Provider.OAUTH))
             .filter(s -> s.getType().equals("user"))
             .peek(s -> log.trace("[{}] matches [{}]? [{}]", s.getValue(), principalName,
-                principalName != null && principalName.matches(s.getValue())))
-            .anyMatch(s -> principalName != null && principalName.matches(s.getValue())))
+               principalName.matches(s.getValue())))
+            .anyMatch(s ->  principalName.matches(s.getValue())))
         .map(Role::getName)
         .collect(Collectors.toSet());