public Optional<File> getReportDir() {
        String reportDirName = resolveProperty(JGIVEN_REPORT_DIR);
        if (reportDirName == null) {
            if (resolveProperty("surefire.test.class.path") != null) {
                reportDirName = "target/jgiven-reports/json";
                log.info(JGIVEN_REPORT_DIR + " not set, but detected surefire plugin, generating reports to "
                    + reportDirName);
            } else {
                reportDirName = "jgiven-reports";
                log.debug(JGIVEN_REPORT_DIR + " not set, using default value jgiven-reports");
            }
        }

        File reportDir = new File(reportDirName);
        if (reportDir.exists() && !reportDir.isDirectory()) {
            log.warn(reportDirName + " exists but is not a directory. Will not generate JGiven reports.");
            return Optional.empty();
        }

        log.debug("Using folder " + reportDirName + " to store JGiven reports");

        return Optional.of(reportDir);
    }
Returns the directory set either via a configuration file or a system property.
If no value is specified and the surefire test classpath is set, the default maven directory will be used,
otherwise a default is returned.
jgiven-core/src/main/java/com/tngtech/jgiven/impl/Config.java