set empty list as default

src/main/java/de/ozgcloud/operator/keycloak/client/OzgKeycloakClientSpec.java

@@ -23,6 +23,7 @@
  */
 package de.ozgcloud.operator.keycloak.client;
 
+import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
 
@@ -56,10 +57,12 @@ class OzgKeycloakClientSpec {
 	private List<String> webOrigins;
 
 	@JsonProperty("client_roles")
-	private List<ClientRole> clientRoles;
+	@Builder.Default
+	private List<ClientRole> clientRoles = new ArrayList<>();
 
 	@JsonProperty("protocol_mappers")
-	private List<ProtocolMapper> protocolMappers;
+	@Builder.Default
+	private List<ProtocolMapper> protocolMappers = new ArrayList<>();
 
 	@Getter
 	@Setter