[gnome-builder] gradle: fix build target usage

[Christian Hergert <chergert src gnome org>]

commit a6af2702c0ad609a3d694b5e1c5a5afbb6402a4f
Author: Christian Hergert <chergert redhat com>
Date:   Mon Jan 21 11:33:42 2019 -0800

    gradle: fix build target usage

 src/plugins/gradle/gradle_plugin.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/src/plugins/gradle/gradle_plugin.py b/src/plugins/gradle/gradle_plugin.py
index 59603e5c2..a937769c1 100755
--- a/src/plugins/gradle/gradle_plugin.py
+++ b/src/plugins/gradle/gradle_plugin.py
@@ -163,7 +163,7 @@ class GradleIdeTestProvider(Ide.TestProvider):
                                          code=Gio.IOErrorEnum.NOT_SUPPORTED))
             return
 
-        task.targets = [GradleBuildTarget(context=self.get_context())]
+        task.targets = [build_system.ensure_child_typed(GradleBuildTarget)]
 
         try:
             runtime = pipeline.get_runtime()