Specifies whether the field supports only internal URLs. File core/modules/link/src/LinkItemInterface

Defines an interface for the link field item. Hierarchy interface \Drupal\Core\TypedData\

Specifies whether the field supports only external URLs. File core/modules/link/src/LinkItemInterface

Specifies whether the field supports both internal and external URLs. File core/modules/link/src/LinkItemInterface

public LinkItemInterface::isExternal()

public LinkItemInterface::getUrl()