Say you have a

    public void setPropertyColumns(String... namesAndDisplayNames) {
        assert namesAndDisplayNames.length % 2 == 0 :
            "Odd number of names and display names: " + //NOI18N
            Arrays.asList(namesAndDisplayNames);

You get a hint to rewrite it to use exceptions (not sure why assertions are bad...).

If you accept the hint, you get:
        if (!namesAndDisplayNames.length % 2 == 0) {
            throw new IllegalStateException("Odd number of names and display names: " + Arrays.asList(namesAndDisplayNames));
        }

It needs to generate either
if (!(namesAndDisplayNames.length % 2 == 0)) {
which is ugly, or
if (namesAndDisplayNames.length % 2 != 0) {
which would be more correct.