fix: check if claims is null to avoid null pointer exception

Author: loichenninger

src/main/java/fr/insee/genesis/configuration/auth/security/OIDCSecurityConfig.java

@@ -85,11 +85,10 @@ public Collection<GrantedAuthority> convert(Jwt source) {
                 String[] claimPath = inseeSecurityTokenProperties.getOidcClaimRole().split("\\.");
                 Map<String, Object> claims = source.getClaims();
                 try {
-                    if (!claims.isEmpty()) {
-                        for (int i = 0; i < claimPath.length - 1; i++) {
-                            claims = (Map<String, Object>) claims.get(claimPath[i]);
-                        }
-
+                    for (int i = 0; i < claimPath.length - 1; i++) {
+                        claims = (Map<String, Object>) claims.get(claimPath[i]);
+                    }
+                    if (claims != null) {
                         List<String> tokenClaims = (List<String>) claims.getOrDefault(claimPath[claimPath.length - 1], List.of());
                         // Collect distinct values from mapping associated with input keys
                         List<String> claimedRoles = tokenClaims.stream()