code: public T setPropertiesFile(final String file) {
          final Path path;
          if (file == null) {
              path = null;
          } else {
              path = Paths.get(file);
          }
          return setPropertiesFile(path);
      }
docs: Sets the properties file to use for the server or {@code null} to remove the file. Note that the file must exist.
  <p>
  This will override any previous values set.
  </p>
  
  @param file the properties file to use or {@code null}
  
  @return the builder
  
  @throws java.lang.IllegalArgumentException if the file does not exist or is not a regular file