code: @Override
      public void initialize(Subject subject, CallbackHandler callbackHandler, Map sharedState, Map options) {
          this.subject = subject;
          this.sharedState = sharedState;
      }
docs: <p>Initialize this login module.</p>
  
  <p>
  This is called by the <code>LoginContext</code> after this login module is
  instantiated. The relevant information is passed from the <code>LoginContext</code>
  to this login module. If the login module does not understands any of the data
  stored in the <code>sharedState</code> and <code>options</code> parameters,
  they can be ignored.
  </p>
  
  @param subject The subject to be authenticated.
  @param callbackHandler
  A <code>CallbackHandler</code> for communicating with the end user to gather login information (e.g., username and password).
  @param sharedState
  The state shared with other configured login modules.
  @param options The options specified in the login configuration for this particular login module.