code: public void setProfile(String profileDirectory) {
      options.get(PROFILE).setValue(PROFILE.sanitize(profileDirectory));
      supportsPd = !(profileDirectory != null && profileDirectory.isEmpty());
    }
docs: Sets the directory to use for the Opera profile.  If string is not empty use the given
  directory.  If string is empty, the <code>-debugproxy</code> command-line argument will be
  disabled for backwards compatibility reasons with older products, such as Opera < 11.60 and
  core-mini.
  
  @param profileDirectory the path to the profile directory
  @throws NullPointerException if argument is null