[FEATURE] First HTTPS support

src/test/java/net/sourceforge/plantuml/servlet/TestProxy.java

@@ -60,6 +60,6 @@ public class TestProxy extends WebappTestCase {
         WebRequest request = new GetMethodWebRequest(getServerUrl() + "proxy?src=invalidURL");
         WebResponse response = conversation.getResource(request);
         // Analyze response, it must be HTTP error 500
-        assertEquals("Response HTTP status is not 500", response.getResponseCode(), 500);
+        assertEquals("Bad HTTP status received", 500, response.getResponseCode());
     }
 }