code: public void addConfigurationSource(ConfigurationSource configurationSource, boolean firstPrio) {
  		if (configurationSource == null) {
  			return;
  		}
  		if (firstPrio) {
  			configurationSources.add(0, configurationSource);
  		} else {
  			configurationSources.add(configurationSource);
  		}
  	}
docs: Adds a configuration source to the configuration.
  <p>
  Don't forget to call {@link #reloadAllConfigurationOptions()} or {@link #reloadDynamicConfigurationOptions()}
  after adding all configuration sources.
  
  @param configurationSource the configuration source to add
  @param firstPrio           whether the configuration source should be first or last priority