@Override
	public String toString() {
		String result = getClass().getSimpleName() + " ";
		if (firstName != null && !firstName.trim().isEmpty())
			result += "firstName: " + firstName;
		if (lastName != null && !lastName.trim().isEmpty())
			result += ", lastName: " + lastName;
		if (userName != null && !userName.trim().isEmpty())
			result += ", userName: " + userName;
		if (password != null && !password.trim().isEmpty())
			result += ", password: " + password;
		return result;
	}