GH-3055 Add additional types for toString() serialization

Add additional types for toString() serialization to Kafka's  to ensure propper serialization/deserialization of message header values.

Resolves #3055

binders/kafka-binder/spring-cloud-stream-binder-kafka/src/main/java/org/springframework/cloud/stream/binder/kafka/BinderHeaderMapper.java

@@ -92,7 +92,9 @@ public class BinderHeaderMapper extends AbstractKafkaHeaderMapper {
 	private static final List<String> DEFAULT_TO_STRING_CLASSES =
 			Arrays.asList(
 					"org.springframework.util.MimeType",
-					"org.springframework.http.MediaType"
+					"org.springframework.http.MediaType",
+					"java.time.OffsetDateTime",
+					"java.net.URI"
 			);
 
 	/**