code: public static List<File> getFiles(File directory)
      {
          Check.notNull(directory);
  
          if (directory.isDirectory())
          {
              final File[] files = directory.listFiles();
              if (files != null)
              {
                  return Arrays.asList(files);
              }
          }
          throw new LionEngineException(ERROR_DIRECTORY + directory.getPath());
      }
docs: Get the files list from directory.
  
  @param directory The directory reference (must not be <code>null</code>).
  @return The directory content.
  @throws LionEngineException If invalid argument or not a directory.