docs: @VisibleForTesting
  	List<File> getProcessConfigFiles() {
  		// TODO : should use a FileVisitor (Once we update to Java 7)
  		File[] files;
  		File configurationDirOrFile = configuration.getProcessConfigDirOrFile();
  		if (configurationDirOrFile == null) {
  			throw new IllegalStateException("Configuration should specify configuration directory or file, with -j of -f option");
  		}
  		if (configurationDirOrFile.isFile()) {
  			files = new File[1];
  			files[0] = configurationDirOrFile;
  		} else {
  			files = firstNonNull(configurationDirOrFile.listFiles(), new File[0]);
  		}
  
  		List<File> result = new ArrayList<>();
  		for (File file : files) {
  			if (this.isProcessConfigFile(file)) {
  				result.add(file);
  			}
  		}
  		return result;
  	}