public static Optional<String> getSearchGraphLocation(final String location, final Storage storage) {
        if (storage.exists(getGraphLocation(location)))
            return Optional.of(getGraphLocation(location));
        else if (storage.exists(location))
            return Optional.of(location);
        else
            return Optional.empty();
    }
@param location not null, not empty UNIX-formatted file system path
@param memoryKey not null, not empty
@return not empty UNIX-formatted file system path to the memory in the location, still compatible with Windows and {@code File}
hadoop-gremlin/src/main/java/org/apache/tinkerpop/gremlin/hadoop/Constants.java