System.setProperty("second.a-double", "2.2");
// execute the example twice. The first time with the prefix
// set to "first". The second time with it set to "second"
SystemConfigurationProvider provider = new SystemConfigurationProvider();
provider.setVariable("prefix", "first");
doWork(provider);
provider.setVariable("prefix", "second");
doWork(provider);
/*
Console will show:
preConfig