The wrong mindset

DefensiveProgramming.java

        int numberOfThingsThatAreSorted = getCustomComparatorNumberOfKnownThingsForSorting();
        int numberOfActualThings = getAllThings().size();
        if (numberOfThingsThatAreSorted < numberOfActualThings)
            throw new IllegalStateException(
                    "An implementation of ThisClass (whose abstract subclasses are ThatOtherClass and YetAnotherClass) "
                            + "must ensure that all the Things it specifies are also passed in for custom sorting. Instead found only "
                            + numberOfThingsThatAreSorted
                            + " Things to be sorted, as implemented by getCustomComparatorNumberOfKnownThingsForSorting, but "
                            + numberOfActualThings + " actual Things.");