JSpecify: Another "Did not find supertype" crash, with Strings

[msridhar]

          > @SolomonSun2010 Do you have an example input program that causes the error? Without that it'll be hard to track down the problem.

@msridhar OK，when running NullAway， normally display :
warning: [NullAway] xxxxxx

Suddenly, error message is:

An unhandled exception was thrown by Error Prone static analysis pluging.
", relativeServices=" + (relativeServices == null ? "relativeServices == null" : relativeServices.size())

    @Override
    public String toString() {
        return "ServiceExtraInfo{" +
            "appInfoData=" + (appInfoData == null ?  "null" : appInfoData.toString()) +
            ", relativeServices=" + (relativeServices == null ? "relativeServices == null" : relativeServices.size())
            + getRelativeServicesToString() + '}';
    }

Originally posted by @SolomonSun2010 in #1008 (comment)