Exception to throw when instance variables are null

I'm working on making a codebase complaint with a list of PMD rules. These include that you're not allowed to throw or catch NullPointerExceptions. I found this method which requires 2 instance variables to be non-null in order to run. It throws a NullPointerException otherwise:

public String build() {
if (apiKey == null || url == null) {
    throw new NullPointerException(
            "Cannot build: API key and URL must be set");
}

What should it be throwing instead? it seems to me that NullPointerException would be the bast call. The only other thing that comes to mind is IllegalArgumentException, but these aren't really arguments, so I don't think it really fits.