Made API reflect the uniqueness of kafka topics.

Author: sauroter

src/main/java/com/hivemq/extensions/kafka/api/services/KafkaTopicService.java

@@ -2,17 +2,18 @@
 
 import com.hivemq.extension.sdk.api.annotations.NotNull;
 
-import java.util.List;
+import java.util.Map;
+import java.util.Set;
 
 public interface KafkaTopicService {
 
     @NotNull KafkaTopicState getKafkaTopicState(@NotNull String topic);
 
-    @NotNull List<@NotNull KafkaTopicState> getKafkaTopicStates(@NotNull List<@NotNull String> topics);
+    @NotNull Map<String, @NotNull KafkaTopicState> getKafkaTopicStates(@NotNull Set<@NotNull String> topics);
 
     @NotNull KafkaTopicState createKafkaTopic(@NotNull String topic);
 
-    @NotNull List<@NotNull KafkaTopicState> createKafkaTopics(@NotNull List<@NotNull String> topics);
+    @NotNull Map<String, @NotNull KafkaTopicState> createKafkaTopics(@NotNull Set<@NotNull String> topics);
 
     enum KafkaTopicState {
         FAILURE, EXISTS, CREATED, MISSING,