MODLOGINKC-19: make non tenant topics optional (#120)

* MODLOGINKC-19: make non tenant topics optional

* add test

* add using emptyIfNull util method

folio-integration-kafka/src/main/java/org/folio/integration/kafka/KafkaTopicConfiguration.java

@@ -1,5 +1,6 @@
 package org.folio.integration.kafka;
 
+import static org.apache.commons.collections4.CollectionUtils.emptyIfNull;
 import static org.folio.integration.kafka.KafkaUtils.getEnvTopicName;
 
 import jakarta.annotation.PostConstruct;
@@ -17,7 +18,7 @@ public class KafkaTopicConfiguration {
 
   @PostConstruct
   public void createTopics() {
-    for (var topic : folioKafkaProperties.getTopics()) {
+    for (var topic : emptyIfNull(folioKafkaProperties.getTopics())) {
       var topicName = getEnvTopicName(topic.getName());
       var newTopic = KafkaUtils.createTopic(topicName, topic.getNumPartitions(), topic.getReplicationFactor());
       kafkaAdminService.createTopic(newTopic);

folio-integration-kafka/src/test/java/org/folio/integration/kafka/KafkaTopicConfigurationTest.java

@@ -1,6 +1,7 @@
 package org.folio.integration.kafka;
 
 import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.verifyNoInteractions;
 import static org.mockito.Mockito.when;
 
 import java.util.List;
@@ -34,4 +35,13 @@ void createTopics_positive() {
     verify(kafkaAdminService).createTopic(new NewTopic("folio.topic2", Optional.empty(), Optional.of((short) 2)));
     verify(kafkaAdminService).createTopic(new NewTopic("folio.topic3", Optional.of(30), Optional.of((short) -1)));
   }
+
+  @Test
+  void createTopics_positive_topicsEmpty() {
+    when(folioKafkaProperties.getTopics()).thenReturn(null);
+
+    kafkaTopicConfiguration.createTopics();
+
+    verifyNoInteractions(kafkaAdminService);
+  }
 }