Merged #1595 and enabled test.

core/src/main/java/hudson/model/Api.java

@@ -208,7 +208,7 @@ public class Api extends AbstractModelObject {
     public void doJson(StaplerRequest req, StaplerResponse rsp) throws IOException, ServletException {
         if (req.getParameter("jsonp") == null || permit(req)) {
             setHeaders(rsp);
-            rsp.serveExposedBean(req,bean, Flavor.JSON);
+            rsp.serveExposedBean(req,bean, req.getParameter("jsonp") == null ? Flavor.JSON : Flavor.JSONP);
         } else {
             rsp.sendError(HttpURLConnection.HTTP_FORBIDDEN, "jsonp forbidden; implement jenkins.security.SecureRequester");
         }

test/src/test/java/hudson/model/ApiTest.java

@@ -29,7 +29,6 @@ import com.gargoylesoftware.htmlunit.Page;
 
 import java.io.File;
 import java.net.HttpURLConnection;
-import org.junit.Ignore;
 
 import org.junit.Rule;
 import org.junit.Test;
@@ -50,7 +49,6 @@ public class ApiTest {
         j.createWebClient().goTo("api/xml?xpath=/*[1]", "application/xml");
     }
 
-    @Ignore("TODO currently serves application/json")
     @Issue("JENKINS-27607")
     @Test public void json() throws Exception {
         FreeStyleProject p = j.createFreeStyleProject("p");