private static String extractFileName(String expression) {
        String fileName = expression.substring("file:".length()).trim();
        if ( ! fileName.endsWith(ApplicationPackage.RANKEXPRESSION_NAME_SUFFIX))
            fileName = fileName + ApplicationPackage.RANKEXPRESSION_NAME_SUFFIX;

        return fileName;
    }
Returns all filter fields in this profile and any profile it inherits.
config-model/src/main/java/com/yahoo/schema/RankProfile.java