code: @Override
    public boolean logout() throws LoginException {
      if (mSubject.isReadOnly()) {
        throw new LoginException("logout Failed: Subject is Readonly.");
      }
  
      if (mUser != null) {
        mSubject.getPrincipals().remove(mUser);
      }
  
      return true;
    }
docs: Logs out the user
  
  <p>
  The implementation removes the User associated with the Subject.
  
  @return true in all cases
  @throws LoginException if logout fails