Allow setting timeout in ResponseBodyEmitter

Issue: SPR-13104

spring-web/src/main/java/org/springframework/web/context/request/async/DeferredResult.java

@@ -78,9 +78,12 @@ public class DeferredResult<T> {
 
 	/**
 	 * Create a DeferredResult with a timeout value.
+	 * <p>By default not set in which case the default configured in the MVC
+	 * Java Config or the MVC namespace is used, or if that's not set, then the
+	 * timeout depends on the default of the underlying server.
 	 * @param timeout timeout value in milliseconds
 	 */
-	public DeferredResult(long timeout) {
+	public DeferredResult(Long timeout) {
 		this(timeout, RESULT_NONE);
 	}