private Boolean checkAllEmpty() { // If base (empty) has an open content, turn it into an "all". int[] idx = new int[]{-1}; if (base.nextWildcardTransition(b, bn, idx) != null) { base = new XS11AllCM(false, 0, null, ((XSEmptyCM)base).getOpenContent()); return null; } // Base allows nothing. Derived must be empty too. return Boolean.valueOf(derived.nextElementTransition(d, dn, idx) == null && derived.nextWildcardTransition(d, dn, idx) == null); }