GH-2135: Fix NPE in JsonDeserializer

Resolves #2135

NPE when getting the package of an array class.

Author: m-ibot

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

@@ -531,7 +531,9 @@ public synchronized void addTrustedPackages(String... packages) {
 
 	private void addMappingsToTrusted(Map<String, Class<?>> mappings) {
 		mappings.values().forEach(clazz -> {
-			String packageName = clazz.isArray() ? clazz.getComponentType().getPackage().getName() : clazz.getPackage().getName();
+			String packageName = clazz.isArray()
+					? clazz.getComponentType().getPackage().getName()
+					: clazz.getPackage().getName();
 			doAddTrustedPackages(packageName);
 			doAddTrustedPackages(packageName + ".*");
 		});

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

@@ -310,6 +310,19 @@ void testTrustMappingPackages() {
 			.contains(Foo.class.getPackageName() + ".*");
 	}
 
+	@SuppressWarnings("unchecked")
+	@Test
+	void testTrustMappingPackagesForArray() {
+		JsonDeserializer<Object> deser = new JsonDeserializer<>();
+		Map<String, Object> props = Collections.singletonMap(JsonDeserializer.TYPE_MAPPINGS,
+				"foo:" + Foo[].class.getName());
+		deser.configure(props, false);
+		assertThat(KafkaTestUtils.getPropertyValue(deser, "typeMapper.trustedPackages", Set.class))
+				.contains(Foo.class.getPackageName());
+		assertThat(KafkaTestUtils.getPropertyValue(deser, "typeMapper.trustedPackages", Set.class))
+			.contains(Foo.class.getPackageName() + ".*");
+	}
+
 	@SuppressWarnings("unchecked")
 	@Test
 	void testTrustMappingPackagesWithAll() {