GH-869: fixed NPE in case of array target types

Fixes #869

* GH-869: replaced spaces with tabs

* GH-869: added @author tag

**Cherry-pick to 2.1.x, 2.0.x * 1.3.x**

Author: oranje42

spring-kafka/src/main/java/org/springframework/kafka/support/serializer/JsonDeserializer.java

@@ -49,6 +49,7 @@
  * @author Gary Russell
  * @author Yanming Zhou
  * @author Elliot Kennedy
+ * @author Torsten Schleede
  */
 public class JsonDeserializer<T> implements ExtendedDeserializer<T> {
 
@@ -208,9 +209,17 @@ public void addTrustedPackages(String... packages) {
 	}
 
 	private void addTargetPackageToTrusted() {
+		String targetPackageName = getTargetPackageName();
+		if (targetPackageName != null) {
+			addTrustedPackages(targetPackageName);
+		}
+	}
+
+	private String getTargetPackageName() {
 		if (this.targetType != null) {
-			addTrustedPackages(this.targetType.getPackage().getName());
+			return ClassUtils.getPackageName(this.targetType).replaceFirst("\\[L", "");
 		}
+		return null;
 	}
 
 	@Override

spring-kafka/src/test/java/org/springframework/kafka/support/serializer/JsonSerializationTests.java

@@ -40,21 +40,28 @@
  * @author Igor Stepanov
  * @author Artem Bilan
  * @author Yanming Zhou
+ * @author Torsten Schleede
  */
 public class JsonSerializationTests {
 
 	private StringSerializer stringWriter;
 
 	private StringDeserializer stringReader;
 
-	private JsonSerializer<DummyEntity> jsonWriter;
+	private JsonSerializer<Object> jsonWriter;
 
 	private JsonDeserializer<DummyEntity> jsonReader;
 
+	private JsonDeserializer<DummyEntity[]> jsonArrayReader;
+
 	private JsonDeserializer<DummyEntity> dummyEntityJsonDeserializer;
 
+	private JsonDeserializer<DummyEntity[]> dummyEntityArrayJsonDeserializer;
+
 	private DummyEntity entity;
 
+	private DummyEntity[] entityArray;
+
 	private String topic;
 
 	@Before
@@ -66,12 +73,16 @@ public void init() {
 		List<String> list = Arrays.asList("dummy1", "dummy2");
 		entity.complexStruct = new HashMap<>();
 		entity.complexStruct.put((short) 4, list);
+		entityArray = new DummyEntity[] { entity };
 
 		topic = "topic-name";
 
 		jsonReader = new JsonDeserializer<DummyEntity>() { };
 		jsonReader.configure(new HashMap<String, Object>(), false);
 		jsonReader.close(); // does nothing, so may be called any time, or not called at all
+		jsonArrayReader = new JsonDeserializer<DummyEntity[]>() { };
+		jsonArrayReader.configure(new HashMap<String, Object>(), false);
+		jsonArrayReader.close(); // does nothing, so may be called any time, or not called at all
 		jsonWriter = new JsonSerializer<>();
 		jsonWriter.configure(new HashMap<String, Object>(), false);
 		jsonWriter.close(); // does nothing, so may be called any time, or not called at all
@@ -80,6 +91,7 @@ public void init() {
 		stringWriter = new StringSerializer();
 		stringWriter.configure(new HashMap<String, Object>(), false);
 		dummyEntityJsonDeserializer = new DummyEntityJsonDeserializer();
+		dummyEntityArrayJsonDeserializer = new DummyEntityArrayJsonDeserializer();
 	}
 
 	/*
@@ -95,6 +107,19 @@ public void testDeserializeSerializedEntityEquals() {
 		assertThat(dummyEntityJsonDeserializer.deserialize(topic, headers, jsonWriter.serialize(topic, entity))).isEqualTo(entity);
 	}
 
+	/*
+	 * 1. Serialize test entity array to byte array.
+	 * 2. Deserialize it back from the created byte array.
+	 * 3. Check the result with the source entity array.
+	 */
+	@Test
+	public void testDeserializeSerializedEntityArrayEquals() {
+		assertThat(jsonArrayReader.deserialize(topic, jsonWriter.serialize(topic, entityArray))).isEqualTo(entityArray);
+		Headers headers = new RecordHeaders();
+		headers.add(AbstractJavaTypeMapper.DEFAULT_CLASSID_FIELD_NAME, DummyEntity[].class.getName().getBytes());
+		assertThat(dummyEntityArrayJsonDeserializer.deserialize(topic, headers, jsonWriter.serialize(topic, entityArray))).isEqualTo(entityArray);
+	}
+
 	/*
 	 * 1. Serialize "dummy" String to byte array.
 	 * 2. Deserialize it back from the created byte array.
@@ -151,4 +176,8 @@ static class DummyEntityJsonDeserializer extends JsonDeserializer<DummyEntity> {
 
 	}
 
+	static class DummyEntityArrayJsonDeserializer extends JsonDeserializer<DummyEntity[]> {
+
+	}
+
 }