@API(status = API.Status.STABLE)
        static <C> @NonNull Simple<C> contains(final boolean ignoreCase) {
            final BiPredicate<String, String> test = ignoreCase
                    ? (suggestion, input) -> suggestion.toLowerCase(Locale.ROOT).contains(input.toLowerCase(Locale.ROOT))
                    : String::contains;
            return Simple.contextFree(test);
        }
Create a filter using {@link String#contains(CharSequence)} that can optionally ignore case.

@param ignoreCase whether to ignore case
@param <C>        sender type
@return new filter
cloud-core/src/main/java/org/incendo/cloud/suggestion/FilteringSuggestionProcessor.java