public RegionLocations get(byte[] startKey) {
    return cache.get(startKey);
  }
Gets the RegionLocations for a given region's startKey. This is a direct lookup, if the key
does not exist in the cache it will return null.
@param startKey region start key to directly look up
hbase-client/src/main/java/org/apache/hadoop/hbase/client/AsyncRegionLocationCache.java