code: public ExtWebDriver getNewSession(String key, String value) throws Exception {
          return getNewSession(key, value, true);
      }
docs: Create and return a new ExtWebDriver instance. The instance is
  constructed with default options, with the provided key/value pair
  overriding the corresponding key and value in the options, and will
  become the current session. This is a convenience method for use when
  only a single option needs to be overridden. If overriding multiple
  options, you must use getNewSession(string-string Map, boolean)
  instead.
  
  @param key
  The key whose default value will be overridden
  @param value
  The value to be associated with the provided key
  @return A new ExtWebDriver instance which is now the current session
  @throws Exception