Block/Cache/Additional.php
public function getContentTypeOptions()
    {
        $contentTypes = [
            self::CONTENT_TYPE_HTML  => __('HTML'),
            self::CONTENT_TYPE_CSS   => __('CSS'),
            self::CONTENT_TYPE_JS    => __('JavaScript'),
            self::CONTENT_TYPE_IMAGE => __('Images')
        ];
        return $contentTypes;
    }
public function getContentTypeOptions()
    {
        $contentTypes = [
            self::CONTENT_TYPE_HTML  => __('HTML'),
            self::CONTENT_TYPE_CSS   => __('CSS'),
            self::CONTENT_TYPE_JS    => __('JavaScript'),
            self::CONTENT_TYPE_IMAGE => __('Images')
        ];
        return $contentTypes;
    }
Get content types as option array

@return array