OZG-5422 initailize realmRoles

ozgcloud-keycloak-operator/src/main/java/de/ozgcloud/operator/keycloak/realm/OzgCloudKeycloakRealmSpec.java

@@ -23,6 +23,7 @@
  */
 package de.ozgcloud.operator.keycloak.realm;
 
+import java.util.ArrayList;
 import java.util.List;
 
 import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
@@ -72,8 +73,8 @@ class OzgCloudKeycloakRealmSpec {
 	}
 
 
-	
-	private List<RealmRole> realmRoles;
+	@Builder.Default
+	private List<RealmRole> realmRoles = new ArrayList<>();
 
 	@Getter
 	@Setter