diff --git a/core/lib/Drupal/Core/Url.php b/core/lib/Drupal/Core/Url.php
index 193a121..4747ed2 100644
--- a/core/lib/Drupal/Core/Url.php
+++ b/core/lib/Drupal/Core/Url.php
@@ -291,9 +291,12 @@ public function setOption($name, $value) {
   }
 
   /**
-   * Returns the path of the URL if it is external.
+   * Returns the external path of the URL.
+   *
+   * Only to be used if self::$external is TRUE.
    *
    * @return string
+   *   The external path.
    */
   public function getPath() {
     return $this->path;
@@ -330,7 +333,7 @@ public function toString() {
    *   An associative array containing all the properties of the route.
    */
   public function toArray() {
-    if ($this->external) {
+    if ($this->isExternal()) {
       return array(
         'path' => $this->getPath(),
         'options' => $this->getOptions(),
@@ -352,7 +355,7 @@ public function toArray() {
    *   An associative array suitable for a render array.
    */
   public function toRenderArray() {
-    if ($this->external) {
+    if ($this->isExternal()) {
       return array(
         '#href' => $this->getPath(),
         '#options' => $this->getOptions(),
diff --git a/core/modules/link/lib/Drupal/link/LinkItemInterface.php b/core/modules/link/lib/Drupal/link/LinkItemInterface.php
index 0a1e55d..afe6cb7 100644
--- a/core/modules/link/lib/Drupal/link/LinkItemInterface.php
+++ b/core/modules/link/lib/Drupal/link/LinkItemInterface.php
@@ -1,6 +1,7 @@
 <?php
 
 /**
+ * @file
  * Contains \Drupal\link\LinkItemInterface.
  */
 
@@ -9,7 +10,7 @@
 use Drupal\Core\Field\ConfigFieldItemInterface;
 
 /**
- * Interface for the link field item.
+ * Defines an interface for the link field item.
  */
 interface LinkItemInterface extends ConfigFieldItemInterface {
 
diff --git a/core/modules/link/lib/Drupal/link/Plugin/Field/FieldWidget/LinkWidget.php b/core/modules/link/lib/Drupal/link/Plugin/Field/FieldWidget/LinkWidget.php
index 4cfecef..9cbede3 100644
--- a/core/modules/link/lib/Drupal/link/Plugin/Field/FieldWidget/LinkWidget.php
+++ b/core/modules/link/lib/Drupal/link/Plugin/Field/FieldWidget/LinkWidget.php
@@ -54,7 +54,7 @@ public function formElement(FieldItemListInterface $items, $delta, array $elemen
       '#required' => $element['#required'],
     );
 
-    // If the field is configured to allows internal paths, it cannot use the
+    // If the field is configured to allow internal paths, it cannot use the
     // 'url' form element and we have to do the validation ourselves.
     if ($url_type & LinkItemInterface::LINK_INTERNAL) {
       $element['url']['#type'] = 'textfield';
diff --git a/core/modules/link/lib/Drupal/link/Tests/LinkFieldTest.php b/core/modules/link/lib/Drupal/link/Tests/LinkFieldTest.php
index b347a9a..d2b0cc7 100644
--- a/core/modules/link/lib/Drupal/link/Tests/LinkFieldTest.php
+++ b/core/modules/link/lib/Drupal/link/Tests/LinkFieldTest.php
@@ -105,10 +105,10 @@ function testURLValidation() {
 
     // Define some valid URLs.
     $valid_external_entries = array(
-      'http://www.example.com/'
+      'http://www.example.com/',
     );
     $valid_internal_entries = array(
-      'entity_test/add'
+      'entity_test/add',
     );
 
     // Define some invalid URLs.
@@ -121,7 +121,7 @@ function testURLValidation() {
       'http://',
     );
     $invalid_internal_entries = array(
-      'non/existing/path'
+      'non/existing/path',
     );
 
     // Test external and internal URLs for 'url_type' = LinkItemInterface::LINK_GENERIC.
@@ -145,7 +145,7 @@ function testURLValidation() {
    * Asserts that valid URLs can be submitted.
    *
    * @param string $field_name
-   *   The field name
+   *   The field name.
    * @param array $valid_entries
    *   An array of valid URL entries.
    */
@@ -168,7 +168,7 @@ protected function assertValidEntries($field_name, array $valid_entries) {
    * Asserts that invalid URLs cannot be submitted.
    *
    * @param string $field_name
-   *   The field name
+   *   The field name.
    * @param array $invalid_entries
    *   An array of invalid URL entries.
    */