fun specifyFactoryIfNotYetSet(reporterFactoryId: String): Unit
Sets Atrium's property with key ATRIUM_PROPERTY_KEY (which is
ch.tutteli.atrium.reporting.reporterFactory) to the given reporterFactoryId
if another id was not yet specified before.
Use specifyFactory if you do not care if another id was specified before or in other words, if you want to overwrite a potentially previously defined id.