code: public T addPropertiesFile(final String file) {
          if (file != null) {
              addPropertiesFile(Paths.get(file));
          }
          return getThis();
      }
docs: Adds a properties file to be passed to the server. Note that the file must exist.
  
  @param file the file to add
  
  @return the builder
  
  @throws java.lang.IllegalArgumentException if the file does not exist or is not a regular file