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;

}