public void setReportDir(File reportDir) {
        System.setProperty(JGIVEN_REPORT_DIR, reportDir.getAbsolutePath());
    }
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