Fix ConcurrentModificationException in GeofenceManager expiry purge

CodenameOne/src/com/codename1/location/GeofenceManager.java

@@ -170,9 +170,10 @@ private synchronized void purgeExpired() {
         boolean saveFences = false;
         boolean saveActive = false;
         boolean saveActiveFences = false;
-        for (Map.Entry<String, Long> time : times.entrySet()) {
+        for (Iterator<Map.Entry<String, Long>> it = times.entrySet().iterator(); it.hasNext();) {
+            Map.Entry<String, Long> time = it.next();
             if (time.getValue() > 0L && time.getValue() < now) {
-                times.remove(time.getKey());
+                it.remove();
                 if (!saveFences && fences.containsKey(time.getKey())) {
                     saveFences = true;
                 }

maven/core-unittests/src/test/java/com/codename1/location/GeofenceManagerTest.java

@@ -126,6 +126,22 @@ void isBubbleRecognizesBubbleId() {
         assertFalse(manager.isBubble("not-bubble"));
     }
 
+    @FormTest
+    void updatePurgesExpiredGeofencesWithoutConcurrentModification() throws Exception {
+        Geofence first = createGeofence("expired-1", 0.0, 0.0, 50, -1L);
+        Geofence second = createGeofence("expired-2", 0.0, 0.0, 50, -1L);
+        manager.add(first, second);
+        Map<String, Long> expirations = new HashMap<String, Long>();
+        long expiredAt = System.currentTimeMillis() - 1000L;
+        expirations.put(first.getId(), expiredAt);
+        expirations.put(second.getId(), expiredAt);
+        setPrivateField("expiryTimes", expirations);
+
+        assertDoesNotThrow(() -> manager.update(1000));
+        assertFalse(manager.asMap().containsKey(first.getId()));
+        assertFalse(manager.asMap().containsKey(second.getId()));
+    }
+
     @FormTest
     public void testGeofenceManagerListener() {
         // Instantiate the listener
@@ -147,6 +163,13 @@ public void testGeofenceManagerListener() {
         assertTrue(MyGeofenceListener.calledEnter, "onEntered should delegate to registered listener");
     }
 
+
+    private void setPrivateField(String name, Object value) throws Exception {
+        Field field = GeofenceManager.class.getDeclaredField(name);
+        field.setAccessible(true);
+        field.set(manager, value);
+    }
+
     private Geofence createGeofence(String id, double lat, double lng, int radius, long expiration) {
         Location location = new Location(lat, lng);
         return new Geofence(id, location, radius, expiration);