#fixed code
                              public static <T> T createFor(final Class<T> protocol, final Actor actor, final Mailbox mailbox) {
    final T maybeCachedProxy = actor.lifeCycle.environment.lookUpProxy(protocol);

    if (maybeCachedProxy != null) {
      return maybeCachedProxy;
    }

    final String proxyClassname = fullyQualifiedClassnameFor(protocol, "__Proxy");

    T newProxy;
    
    try {
      newProxy = tryCreate(protocol, actor, mailbox, proxyClassname);
    } catch (Exception e) {
      synchronized (protocol) {
        newProxy = tryGenerateCreate(protocol, actor, mailbox, proxyClassname);
      }
    }
    
    actor.lifeCycle.environment.cacheProxy(newProxy);
    
    return newProxy;
  }
#vulnerable code 
                              public static <T> T createFor(final Class<T> protocol, final Actor actor, final Mailbox mailbox) {
    final T maybeCachedProxy = actor.lifeCycle.environment.lookUpProxy(protocol);

    if (maybeCachedProxy != null) {
      return maybeCachedProxy;
    }

    final String proxyClassname = fullyQualifiedClassnameFor(protocol, "__Proxy");

    final T maybeProxy = tryProxyFor(proxyClassname, actor, mailbox);

    if (maybeProxy != null) {
      actor.lifeCycle.environment.cacheProxy(maybeProxy);
      return maybeProxy;
    }

    synchronized (protocol) {
      T newProxy;
      
      try {
        newProxy = tryCreate(protocol, actor, mailbox, proxyClassname);
      } catch (Exception e) {
        newProxy = tryGenerateCreate(protocol, actor, mailbox, proxyClassname);
      }
      
      actor.lifeCycle.environment.cacheProxy(newProxy);
      
      return newProxy;
    }
  } 
                            #location 10 
                            #vulnerability type THREAD_SAFETY_VIOLATION