Revert AnnotationGatewayProxyFactoryBean logic

The `AnnotationGatewayProxyFactoryBean` can be configured via setters
and via annotation in the provided interface.

* Override `setProxyDefaultMethods()` to `true` only if annotation explicitly
provides `true`

Author: artembilan

spring-integration-core/src/main/java/org/springframework/integration/gateway/AnnotationGatewayProxyFactoryBean.java

@@ -95,7 +95,10 @@ protected void onInit() {
 
 		populateAsyncExecutorIfAny();
 
-		setProxyDefaultMethods(this.gatewayAttributes.getBoolean("proxyDefaultMethods"));
+		boolean proxyDefaultMethods = this.gatewayAttributes.getBoolean("proxyDefaultMethods");
+		if (proxyDefaultMethods) { // Override only if annotation attribute is different
+			setProxyDefaultMethods(true);
+		}
 		super.onInit();
 	}