KAFKA-8455: Add VoidSerde to Serdes (#7485)

Reviewers: A. Sophie Blee-Goldman <sophie@confluent.io>, Matthias J. Sax <matthias@confluent.io>

clients/src/main/java/org/apache/kafka/common/serialization/Serdes.java

@@ -59,6 +59,12 @@ public class Serdes {
         }
     }
 
+    static public final class VoidSerde extends WrapperSerde<Void> {
+        public VoidSerde() {
+            super(new VoidSerializer(), new VoidDeserializer());
+        }
+    }
+
     static public final class LongSerde extends WrapperSerde<Long> {
         public LongSerde() {
             super(new LongSerializer(), new LongDeserializer());
@@ -252,4 +258,11 @@ public class Serdes {
     static public Serde<byte[]> ByteArray() {
         return new ByteArraySerde();
     }
+
+    /*
+     * A serde for {@code Void} type.
+     */
+    static public Serde<Void> Void() {
+        return new VoidSerde();
+    }
 }

clients/src/main/java/org/apache/kafka/common/serialization/VoidDeserializer.java

@@ -0,0 +1,27 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.kafka.common.serialization;
+
+public class VoidDeserializer implements Deserializer<Void> {
+    @Override
+    public Void deserialize(String topic, byte[] data) {
+        if (data != null)
+            throw new IllegalArgumentException("Data should be null for a VoidDeserializer.");
+
+        return null;
+    }
+}

clients/src/main/java/org/apache/kafka/common/serialization/VoidSerializer.java

@@ -0,0 +1,24 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.kafka.common.serialization;
+
+public class VoidSerializer implements Serializer<Void> {
+    @Override
+    public byte[] serialize(String topic, Void data) {
+        return null;
+    }
+}

clients/src/test/java/org/apache/kafka/common/serialization/SerializationTest.java

@@ -147,6 +147,27 @@ public class SerializationTest {
         }
     }
 
+    @Test
+    public void testSerializeVoid() {
+        try (Serde<Void> serde = Serdes.Void()) {
+            serde.serializer().serialize(topic, null);
+        }
+    }
+
+    @Test
+    public void testDeserializeVoid() {
+        try (Serde<Void> serde = Serdes.Void()) {
+            serde.deserializer().deserialize(topic, null);
+        }
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void voidDeserializerShouldThrowOnNotNullValues() {
+        try (Serde<Void> serde = Serdes.Void()) {
+            serde.deserializer().deserialize(topic, new byte[5]);
+        }
+    }
+
     private Serde<String> getStringSerde(String encoder) {
         Map<String, Object> serializerConfigs = new HashMap<String, Object>();
         serializerConfigs.put("key.serializer.encoding", encoder);