#vulnerable code 
                                @Override
    public boolean compareAndSet(long expect, long update) {
        RedisConnection<String, Object> conn = connectionManager.connection();
        try {
            while (true) {
                conn.watch(getName());
                Long value = (Long) conn.get(getName());
                if (value != expect) {
                    conn.discard();
                    return false;
                }
                conn.multi();
                conn.set(getName(), update);
                if (conn.exec().size() == 1) {
                    return true;
                }
            }
        } finally {
            connectionManager.release(conn);
        }
    } 
                            #location 8 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                @Override
    public boolean compareAndSet(long expect, long update) {
        RedisConnection<String, Object> conn = connectionManager.connection();
        try {
            while (true) {
                conn.watch(getName());
                Long value = ((Number) conn.get(getName())).longValue();
                if (value != expect) {
                    conn.discard();
                    return false;
                }
                conn.multi();
                conn.set(getName(), update);
                if (conn.exec().size() == 1) {
                    return true;
                }
            }
        } finally {
            connectionManager.release(conn);
        }
    }