GH-1858: Fix Regression in JsonDeserializer

Resolves #1858

Do not add mapping class packages if trusted packages is already all (`*`).

**cherry-pick to 2.7.x**

Author: garyrussell

spring-kafka/src/main/java/org/springframework/kafka/support/converter/DefaultJackson2JavaTypeMapper.java

@@ -78,6 +78,9 @@ public void setTypePrecedence(TypePrecedence typePrecedence) {
 	 */
 	@Override
 	public void addTrustedPackages(String... packagesToTrust) {
+		if (this.trustedPackages.size() == 0) {
+			return;
+		}
 		if (packagesToTrust != null) {
 			for (String trusted : packagesToTrust) {
 				if ("*".equals(trusted)) {

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

@@ -304,6 +304,17 @@ void testTrustMappingPackages() {
 			.contains(Foo.class.getPackageName() + ".*");
 	}
 
+	@SuppressWarnings("unchecked")
+	@Test
+	void testTrustMappingPackagesWithAll() {
+		JsonDeserializer<Object> deser = new JsonDeserializer<>();
+		Map<String, Object> props = Map.of(
+				JsonDeserializer.TRUSTED_PACKAGES, "*",
+				JsonDeserializer.TYPE_MAPPINGS, "foo:" + Foo.class.getName());
+		deser.configure(props, false);
+		assertThat(KafkaTestUtils.getPropertyValue(deser, "typeMapper.trustedPackages", Set.class)).isEmpty();
+	}
+
 	@SuppressWarnings("unchecked")
 	@Test
 	void testTrustMappingPackagesMapper() {