/**
     * Returns a view of this supplier that may calculate its value as empty if it would be missing.
     */
    MapSupplier<K, V> absentIgnoring();

    default MapSupplier<K, V> absentIgnoringIfNeeded(boolean required) {
        return required ? absentIgnoring() : this;
    }

    ExecutionTimeValue<? extends Map<K, V>> calculateExecutionTimeValue();

    /**
     * Convenience method that returns a view of this collector that never returns a missing value,
     * if that capability is required, or this very collector.
     */
    default Collector<T> absentIgnoringIfNeeded(boolean required) {
        return required ? absentIgnoring() : this;
    }

    MapCollector<K, V> absentIgnoring();

    /**
     * Returns a collector that may never return a missing value.
     */
    default MapCollector<K, V> absentIgnoringIfNeeded(boolean ignoreAbsent) {
        return ignoreAbsent ? absentIgnoring() : this;
    }

     * if required. If not required, or this supplier already ignores absent results, returns this supplier.
     */
    default CollectionSupplier<T, C> absentIgnoringIfNeeded(boolean required) {
        return required ? absentIgnoring() : this;
    }