added wrapping to mono (#227)

kafka-ui-api/src/main/java/com/provectus/kafka/ui/kafka/KafkaService.java

@@ -208,12 +208,13 @@ public class KafkaService {
     }
 
     public Mono<ExtendedAdminClient> createAdminClient(KafkaCluster kafkaCluster) {
-        Properties properties = new Properties();
-        properties.putAll(kafkaCluster.getProperties());
-        properties.put(AdminClientConfig.BOOTSTRAP_SERVERS_CONFIG, kafkaCluster.getBootstrapServers());
-        properties.put(AdminClientConfig.REQUEST_TIMEOUT_MS_CONFIG, clientTimeout);
-        AdminClient adminClient = AdminClient.create(properties);
-        return ExtendedAdminClient.extendedAdminClient(adminClient);
+        return Mono.fromSupplier(() -> {
+            Properties properties = new Properties();
+            properties.putAll(kafkaCluster.getProperties());
+            properties.put(AdminClientConfig.BOOTSTRAP_SERVERS_CONFIG, kafkaCluster.getBootstrapServers());
+            properties.put(AdminClientConfig.REQUEST_TIMEOUT_MS_CONFIG, clientTimeout);
+            return AdminClient.create(properties);
+        }).flatMap(ExtendedAdminClient::extendedAdminClient);
     }
 
     @SneakyThrows