SlevomatCodingStandard\Helpers\SniffSettingsHelper::normalizeArray PHP Method

    public static function normalizeArray(array $settings)
    {
        $settings = array_map(function ($value) {
            return trim($value);
        }, $settings);
        $settings = array_filter($settings, function ($value) {
            return $value !== '';
        });
        return array_values($settings);
    }

 /**
  * @return string[]
  */
 private function getNamespacesRequiredToUse()
 {
     if ($this->namespacesRequiredToUse !== null && $this->normalizedNamespacesRequiredToUse === null) {
         $this->normalizedNamespacesRequiredToUse = SniffSettingsHelper::normalizeArray($this->namespacesRequiredToUse);
     }
     return $this->normalizedNamespacesRequiredToUse;
 }