Avoid creating InfoWindow iterator if no InfoWindows are shown

platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/maps/InfoWindowManager.java

@@ -22,21 +22,20 @@
  */
 class InfoWindowManager {
 
-  private List<InfoWindow> infoWindows;
+  private final List<InfoWindow> infoWindows = new ArrayList<>();
+
   private MapboxMap.InfoWindowAdapter infoWindowAdapter;
   private boolean allowConcurrentMultipleInfoWindows;
 
   private MapboxMap.OnInfoWindowClickListener onInfoWindowClickListener;
   private MapboxMap.OnInfoWindowLongClickListener onInfoWindowLongClickListener;
   private MapboxMap.OnInfoWindowCloseListener onInfoWindowCloseListener;
 
-  InfoWindowManager() {
-    this.infoWindows = new ArrayList<>();
-  }
-
   void update() {
-    for (InfoWindow infoWindow : infoWindows) {
-      infoWindow.update();
+    if (!infoWindows.isEmpty()) {
+      for (InfoWindow infoWindow : infoWindows) {
+        infoWindow.update();
+      }
     }
   }
 
@@ -56,10 +55,6 @@ boolean isAllowConcurrentMultipleOpenInfoWindows() {
     return allowConcurrentMultipleInfoWindows;
   }
 
-  List<InfoWindow> getInfoWindows() {
-    return infoWindows;
-  }
-
   boolean isInfoWindowValidForMarker(@NonNull Marker marker) {
     return !TextUtils.isEmpty(marker.getTitle()) || !TextUtils.isEmpty(marker.getSnippet());
   }