PropertiesConfiguration simpleConfiguration = new PropertiesConfiguration();
FileHandler handler = new FileHandler(simpleConfiguration);
handler.setFileName(simpleConfigurationFile);
handler.load();
CombinedConfigurationBuilder builder = new CombinedConfigurationBuilder();
builder.configure(new FileBasedBuilderParametersImpl().setFileName(compositeConfigurationFile));
Configuration compositeConfiguration = builder.getConfiguration();
simpleConfiguration.setProperty("prefix.Co.test", Boolean.TRUE);
simpleConfiguration.setProperty("prefix.Av.test", Boolean.TRUE);
compositeConfiguration.setProperty("prefix.Co.test", Boolean.TRUE);