navigator id

lib/android/app/src/main/java/com/reactnativenavigation/viewcontrollers/Navigator.java

 import android.view.View;
 import android.widget.FrameLayout;
 
+import com.reactnativenavigation.utils.CompatUtils;
+
 public class Navigator extends ViewController {
 	private boolean activityResumed = false;
 
 	public Navigator(final Activity activity) {
-		super(activity, "navigator");
+		super(activity, "navigator" + CompatUtils.generateViewId());
 	}
 
 	@NonNull

lib/android/app/src/test/java/com/reactnativenavigation/viewcontrollers/NavigatorTest.java

 import org.junit.Test;
 import org.robolectric.Shadows;
 
+import java.util.regex.Pattern;
+
 import static org.assertj.core.api.Java6Assertions.assertThat;
 
 public class NavigatorTest extends BaseTest {
 		assertHasSingleChildViewOf(child2);
 	}
 
+	@Test
+	public void holdsUniqueId() throws Exception {
+		assertThat(uut.getId()).startsWith("navigator").matches(Pattern.compile("navigator\\d"));
+		assertThat(new Navigator(activity).getId()).isNotEqualTo(uut.getId());
+	}
+
 	private void assertHasSingleChildViewOf(ViewController vc) {
 		assertThat(uut.getView().getChildCount()).isEqualTo(1);
 		assertThat(uut.getView().getChildAt(0)).isEqualTo(vc.getView()).isNotNull();