Fixed ConcurrentModificationException on socket broadcast

src/main/java/ch/usi/inf/sa4/sanmarinoes/smarthut/socket/SensorSocketEndpoint.java

@@ -1,6 +1,5 @@
 package ch.usi.inf.sa4.sanmarinoes.smarthut.socket;
 
-import static ch.usi.inf.sa4.sanmarinoes.smarthut.utils.Utils.didThrow;
 
 import ch.usi.inf.sa4.sanmarinoes.smarthut.config.GsonConfig;
 import ch.usi.inf.sa4.sanmarinoes.smarthut.models.User;
@@ -8,7 +7,6 @@ import com.google.common.collect.HashMultimap;
 import com.google.common.collect.Multimap;
 import com.google.common.collect.Multimaps;
 import com.google.gson.Gson;
-
 import java.io.IOException;
 import java.util.*;
 import javax.websocket.*;
@@ -61,28 +59,19 @@ public class SensorSocketEndpoint extends Endpoint {
      */
     public void broadcast(Object message, User u) {
         final HashSet<Session> sessions = new HashSet<>(authorizedClients.get(u));
-
+        for (Session s : sessions) {
-
-
-        sessions.stream()
-                .filter(
-                        s -> {
-                            if (s.isOpen()) return true;
-                            sessions.remove(s);
-                            return false;
-                        })
-                .forEach(s -> {
-                    synchronized (this){
             try {
+                if (s.isOpen()) {
                     s.getBasicRemote().sendText(gson.toJson(message));
+                } else {
+                    authorizedClients.remove(u, s);
+                }
             } catch (IOException e) {
                 e.printStackTrace();
             }
         }
-                });
     }
 
-
     /**
      * Handles the opening of a socket session with a client
      *