private static Pattern toRegularExpression(final String storagePattern) {
        return Pattern.compile(storagePattern.replace(".", "\\.")
                                             .replace("?", ".")
                                             .replace("*", ".*"));
    }
@param storagePattern not null, not empty pattern in the abstract {@link Storage}
@return non-null regular expression to match local file system paths as strings
spark-gremlin/src/main/java/org/apache/tinkerpop/gremlin/spark/structure/io/SparkContextStorage.java