public Region findRegionByKey(final byte[] key) {
        Requires.requireNonNull(key, "key");
        final StampedLock stampedLock = this.stampedLock;
        final long stamp = stampedLock.readLock();
        try {
            return findRegionByKeyWithoutLock(key);
        } finally {
            stampedLock.unlockRead(stamp);
        }
    }
Returns the region to which the key belongs.
jraft-rheakv/rheakv-core/src/main/java/com/alipay/sofa/jraft/rhea/client/RegionRouteTable.java