added synchronization in RaceStateChangedListeners with a working copy of listeners to avoid ConcurrentModificationException

Change-Id: I8875826f61f76cd55831e57a55afc043017a1d7c

java/com.sap.sailing.domain.shared.android/src/com/sap/sailing/domain/abstractlog/race/state/impl/RaceStateChangedListeners.java

@@ -9,79 +9,105 @@ public class RaceStateChangedListeners extends HashSet<RaceStateChangedListener>
     
     private static final long serialVersionUID = 2028183211903975659L;
 
+    @Override
+    public boolean add(RaceStateChangedListener listener) {
+        synchronized (this) {
+            return super.add(listener);
+        }
+    }
+    
+    @Override
+    public boolean remove(Object o) {
+        synchronized (this) {
+            return super.remove(o);
+        }
+    }
+
+    /**
+     * Produces a working copy that can safely be iterated over. While producing, holds this objects
+     * monitor using {@code synchronized(this)} which teams with {@link #add(RaceStateChangedListener)} and
+     * {@link #remove} which
+     * also synchronized on {@code this} object.
+     */
+    private Iterable<RaceStateChangedListener> getWorkingCopyOfListeners() {
+        synchronized (this) {
+            return new HashSet<>(this);
+        }
+    }
+    
     @Override
     public void onRacingProcedureChanged(ReadonlyRaceState state) {
-        for (RaceStateChangedListener listener : this) {
+        for (RaceStateChangedListener listener : getWorkingCopyOfListeners()) {
             listener.onRacingProcedureChanged(state);
         }
     }
 
     @Override
     public void onStatusChanged(ReadonlyRaceState state) {
-        for (RaceStateChangedListener listener : this) {
+        for (RaceStateChangedListener listener : getWorkingCopyOfListeners()) {
             listener.onStatusChanged(state);
         }
     }
 
     @Override
     public void onStartTimeChanged(ReadonlyRaceState state) {
-        for (RaceStateChangedListener listener : this) {
+        for (RaceStateChangedListener listener : getWorkingCopyOfListeners()) {
             listener.onStartTimeChanged(state);
         }
     }
 
     @Override
     public void onFinishingTimeChanged(ReadonlyRaceState state) {
-        for (RaceStateChangedListener listener : this) {
+        for (RaceStateChangedListener listener : getWorkingCopyOfListeners()) {
             listener.onFinishingTimeChanged(state);
         }
     }
 
     @Override
     public void onFinishedTimeChanged(ReadonlyRaceState state) {
-        for (RaceStateChangedListener listener : this) {
+        for (RaceStateChangedListener listener : getWorkingCopyOfListeners()) {
             listener.onFinishedTimeChanged(state);
         }
     }
 
     @Override
     public void onProtestTimeChanged(ReadonlyRaceState state) {
-        for (RaceStateChangedListener listener : this) {
+        for (RaceStateChangedListener listener : getWorkingCopyOfListeners()) {
             listener.onProtestTimeChanged(state);
         }
     }
 
     @Override
     public void onAdvancePass(ReadonlyRaceState state) {
-        for (RaceStateChangedListener listener : this) {
+        for (RaceStateChangedListener listener : getWorkingCopyOfListeners()) {
             listener.onAdvancePass(state);
         }
     }
 
     @Override
     public void onFinishingPositioningsChanged(ReadonlyRaceState state) {
-        for (RaceStateChangedListener listener : this) {
+        for (RaceStateChangedListener listener : getWorkingCopyOfListeners()) {
             listener.onFinishingPositioningsChanged(state);
         }
     }
 
     @Override
     public void onFinishingPositionsConfirmed(ReadonlyRaceState state) {
-        for (RaceStateChangedListener listener : this) {
+        for (RaceStateChangedListener listener : getWorkingCopyOfListeners()) {
             listener.onFinishingPositionsConfirmed(state);
         }
     }
 
     @Override
     public void onCourseDesignChanged(ReadonlyRaceState state) {
-        for (RaceStateChangedListener listener : this) {
+        for (RaceStateChangedListener listener : getWorkingCopyOfListeners()) {
             listener.onCourseDesignChanged(state);
         }
     }
 
     @Override
     public void onWindFixChanged(ReadonlyRaceState state) {
-        for (RaceStateChangedListener listener : this) {
+        for (RaceStateChangedListener listener : getWorkingCopyOfListeners()) {
             listener.onWindFixChanged(state);
         }
     }