lwjgl test: fix build exceed timeout

jme3-lwjgl/src/test/java/com/jme3/app/LwjglAppTest.java

@@ -30,6 +30,7 @@
  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 package com.jme3.app;
+
 import com.jme3.renderer.RenderManager;
 import com.jme3.system.JmeContext;
 import java.awt.GraphicsEnvironment;
@@ -69,15 +70,19 @@ public class LwjglAppTest {
         app.setLostFocusBehavior(LostFocusBehavior.Disabled);
 
         // start the application - simple init / update will be called once.
-        app.start(type, true); assert app.isStarted();
+        app.start(type, true);
+        assert app.isStarted();
 
         // stop the application, wait a bit, then start it again.
-        app.stop(true);  assert !app.isStarted();
+        app.stop(true);
+        assert !app.isStarted();
 
         Thread.sleep(100);
 
-        app.start(type, true); assert app.isStarted();
-        app.stop(true);  assert !app.isStarted();
+        app.start(type, true);
+        assert app.isStarted();
+        app.stop(true);
+        assert !app.isStarted();
 
         // make sure each method was called twice.
         assertEquals(2, simpleInitAppInvocations.get());
@@ -98,6 +103,7 @@ public class LwjglAppTest {
 
     @Test
     public void testOffscreenSurface() throws InterruptedException {
+        assumeFalse(GraphicsEnvironment.isHeadless());
         doStopStart(new TestApp(), JmeContext.Type.OffscreenSurface);
     }