@Override
    public void close() {
        this.lock.writeLock().lock();
        try {
            this.closed = true;
        } finally {
            this.lock.writeLock().unlock();
        }
    }
An implementation of {@link Messenger} using SQL.
common/src/main/java/me/lucko/luckperms/common/messaging/sql/AbstractSqlMessenger.java