interface LinkItemInterface

interface LinkItemInterface extends FieldItemInterface {
    
    /**
     * Specifies whether the field supports only internal URLs.
     */
    const LINK_INTERNAL = 0x1;
    
    /**
     * Specifies whether the field supports only external URLs.
     */
    const LINK_EXTERNAL = 0x10;
    
    /**
     * Specifies whether the field supports both internal and external URLs.
     */
    const LINK_GENERIC = 0x11;
    
    /**
     * Determines if a link is external.
     *
     * @return bool
     *   TRUE if the link is external, FALSE otherwise.
     */
    public function isExternal();
    
    /**
     * Gets the URL object.
     *
     * @return \Drupal\Core\Url
     *   Returns a Url object.
     *
     * @throws \InvalidArgumentException
     *   Thrown when there is a problem with field data.
     */
    public function getUrl();
    
    /**
     * Gets the link title.
     *
     * @return string|null
     *   Returns the link title.
     */
    public function getTitle() : ?string;

}