[gnome-builder] maven: fix build target usage

[Christian Hergert <chergert src gnome org>]

commit de207ddd91093cf9a86cc92736c1effeda52b579
Author: Christian Hergert <chergert redhat com>
Date:   Mon Jan 21 11:33:50 2019 -0800

    maven: fix build target usage

 src/plugins/maven/maven_plugin.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/src/plugins/maven/maven_plugin.py b/src/plugins/maven/maven_plugin.py
index fda913272..447abe58e 100755
--- a/src/plugins/maven/maven_plugin.py
+++ b/src/plugins/maven/maven_plugin.py
@@ -144,7 +144,7 @@ class MavenBuildTargetProvider(Ide.Object, Ide.BuildTargetProvider):
                                          code=Gio.IOErrorEnum.NOT_SUPPORTED))
             return
 
-        task.targets = [MavenBuildTarget(context=self.get_context())]
+        task.targets = [build_system.ensure_child_typed(MavenBuildTarget)]
         task.return_boolean(True)
 
     def do_get_targets_finish(self, result):
@@ -166,7 +166,7 @@ class MavenIdeTestProvider(Ide.TestProvider):
                                          code=Gio.IOErrorEnum.NOT_SUPPORTED))
             return
 
-        task.targets = [MavenBuildTarget(context=self.get_context())]
+        task.targets = [build_system.ensure_child_typed(MavenBuildTarget)]
 
         try:
             runtime = pipeline.get_runtime()