code: @Nullable
      @Override
      public R findCounterExample(A automaton, Collection<? extends I> inputs, P property) {
          if (automaton.size() > size) {
              counterExamples.clear();
          }
  
          size = automaton.size();
  
          return counterExamples.computeIfAbsent(
                  Pair.of(inputs, property),
                  key -> Optional.ofNullable(modelChecker.findCounterExample(automaton, inputs, property))).orElse(null);
      }
docs: The cached implementation for finding counter examples.
  
  @see ModelChecker#findCounterExample(Object, Collection, Object)