protected function updateMap(array &$aMap, string $sKey, array $aValues): self
    {
        if (!array_key_exists($sKey, $aMap)) {
            $aMap[$sKey] = [];
        }

        $aMap[$sKey] = array_values(
            array_unique(
                array_merge(
                    $aMap[$sKey],
                    $aValues
                )
            )
        );

        return $this;
    }