code: protected static void deleteFile(@Nonnull final File file) {
  		Check.notNull(file, "file");
  		Check.stateIsTrue(!file.exists() || file.delete(), "Cannot delete file '%s'.", file.getPath());
  	}
docs: Removes the given file.
  
  @param file
  a file which should be deleted
  
  @throws net.sf.qualitycheck.exception.IllegalNullArgumentException
  if the given argument is {@code null}
  @throws net.sf.qualitycheck.exception.IllegalStateOfArgumentException
  if the file can not be deleted