Create v3

streams-bootstrap-picocli/src/main/java/com/bakdata/kafka/KafkaApplication.java

@@ -24,11 +24,12 @@
 
 package com.bakdata.kafka;
 
+import static java.util.Collections.emptyMap;
+
 import com.google.common.base.Preconditions;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
-import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
@@ -87,15 +88,15 @@ public abstract class KafkaApplication<R extends Runner, CR extends CleanUpRunne
     @CommandLine.Option(names = "--output-topic", description = "Output topic")
     private String outputTopic;
     @CommandLine.Option(names = "--extra-output-topics", split = ",", description = "Additional named output topics")
-    private Map<String, String> extraOutputTopics = new HashMap<>();
+    private Map<String, String> extraOutputTopics = emptyMap();
     @CommandLine.Option(names = "--brokers", required = true, description = "Broker addresses to connect to")
     private String brokers;
     @CommandLine.Option(names = "--debug", arity = "0..1", description = "Configure logging to debug")
     private boolean debug;
     @CommandLine.Option(names = "--schema-registry-url", description = "URL of Schema Registry")
     private String schemaRegistryUrl;
     @CommandLine.Option(names = "--kafka-config", split = ",", description = "Additional Kafka properties")
-    private Map<String, String> kafkaConfig = new HashMap<>();
+    private Map<String, String> kafkaConfig = emptyMap();
 
     /**
      * <p>This methods needs to be called in the executable custom application class inheriting from

streams-bootstrap-picocli/src/main/java/com/bakdata/kafka/KafkaStreamsApplication.java

@@ -24,8 +24,9 @@
 
 package com.bakdata.kafka;
 
-import java.util.ArrayList;
-import java.util.HashMap;
+import static java.util.Collections.emptyList;
+import static java.util.Collections.emptyMap;
+
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
@@ -67,16 +68,16 @@ public abstract class KafkaStreamsApplication extends
         KafkaApplication<StreamsRunner, StreamsCleanUpRunner, StreamsExecutionOptions,
                 ExecutableStreamsApp<StreamsApp>, ConfiguredStreamsApp<StreamsApp>, StreamsTopicConfig, StreamsApp> {
     @CommandLine.Option(names = "--input-topics", description = "Input topics", split = ",")
-    private List<String> inputTopics = new ArrayList<>();
+    private List<String> inputTopics = emptyList();
     @CommandLine.Option(names = "--input-pattern", description = "Input pattern")
     private Pattern inputPattern;
     @CommandLine.Option(names = "--error-topic", description = "Error topic")
     private String errorTopic;
     @CommandLine.Option(names = "--extra-input-topics", split = ",", description = "Additional named input topics",
             converter = {UseDefaultConverter.class, StringListConverter.class})
-    private Map<String, List<String>> extraInputTopics = new HashMap<>();
+    private Map<String, List<String>> extraInputTopics = emptyMap();
     @CommandLine.Option(names = "--extra-input-patterns", split = ",", description = "Additional named input patterns")
-    private Map<String, Pattern> extraInputPatterns = new HashMap<>();
+    private Map<String, Pattern> extraInputPatterns = emptyMap();
     @CommandLine.Option(names = "--volatile-group-instance-id", arity = "0..1",
             description = "Whether the group instance id is volatile, i.e., it will change on a Streams shutdown.")
     private boolean volatileGroupInstanceId;