@Override
	public boolean equals(Object obj) {
		if (this == obj) {
			return true;
		}
		if (obj == null) {
			return false;
		}
		if (getClass() != obj.getClass()) {
			return false;
		}

		User other = (User) obj;

		if (userId == null) {
			return other.userId == null;
		}
		return userId.equals(other.userId);
	}
Check this user is valid.

@return true if valid
ngrinder-core/src/main/java/org/ngrinder/model/User.java