diff --git a/core/modules/field/lib/Drupal/field/FieldInfo.php b/core/modules/field/lib/Drupal/field/FieldInfo.php
index e6411c3..8603d9f 100644
--- a/core/modules/field/lib/Drupal/field/FieldInfo.php
+++ b/core/modules/field/lib/Drupal/field/FieldInfo.php
@@ -164,7 +164,7 @@ public function flush() {
   /**
    * Collects a lightweight map of fields across bundles.
    *
-   * @return
+   * @return array
    *   An array keyed by entity type. Each value is an array which keys are
    *   field names and value is an array with two entries:
    *   - type: The field type.
@@ -218,7 +218,7 @@ public function getFieldMap() {
   /**
    * Returns all active fields, including deleted ones.
    *
-   * @return
+   * @return \Drupal\field\FieldInterface[]
    *   An array of field definitions, keyed by field ID.
    */
   public function getFields() {
@@ -256,10 +256,10 @@ public function getFields() {
   /**
    * Retrieves all active, non-deleted instances definitions.
    *
-   * @param $entity_type
+   * @param string $entity_type
    *   (optional) The entity type.
    *
-   * @return
+   * @return array
    *   If $entity_type is not set, all instances keyed by entity type and bundle
    *   name. If $entity_type is set, all instances for that entity type, keyed
    *   by bundle name.
@@ -310,7 +310,7 @@ public function getInstances($entity_type = NULL) {
    * @param string $field_name
    *   The field name.
    *
-   * @return
+   * @return \Drupal\field\FieldInterface|NULL
    *   The field definition, or NULL if no field was found.
    */
   public function getField($entity_type, $field_name) {
@@ -345,10 +345,10 @@ public function getField($entity_type, $field_name) {
    *
    * This method only retrieves active fields, deleted or not.
    *
-   * @param $field_id
+   * @param string $field_id
    *   The field ID.
    *
-   * @return
+   * @return \Drupal\field\FieldInterface|NULL
    *   The field definition, or NULL if no field was found.
    */
   public function getFieldById($field_id) {
@@ -387,12 +387,12 @@ public function getFieldById($field_id) {
    * The function also populates the corresponding field definitions in the
    * "static" cache.
    *
-   * @param $entity_type
+   * @param string $entity_type
    *   The entity type.
-   * @param $bundle
+   * @param string $bundle
    *   The bundle name.
    *
-   * @return
+   * @return \Drupal\field\FieldInstanceInterface[]
    *   The array of instance definitions, keyed by field name.
    */
   public function getBundleInstances($entity_type, $bundle) {
@@ -508,8 +508,8 @@ public function getBundleInstances($entity_type, $bundle) {
    * @param string $field_name
    *   The field name for the instance.
    *
-   * @return array
-   *   An associative array of instance data for the specific field and bundle;
+   * @return \Drupal\field\FieldInstanceInterface|NULL
+   *   The instance definition for the specific field of the entity bundle;
    *   NULL if the instance does not exist.
    */
   function getInstance($entity_type, $bundle, $field_name) {
@@ -522,12 +522,12 @@ function getInstance($entity_type, $bundle, $field_name) {
   /**
    * Retrieves the "extra fields" for a bundle.
    *
-   * @param $entity_type
+   * @param string $entity_type
    *   The entity type.
-   * @param $bundle
+   * @param string $bundle
    *   The bundle name.
    *
-   * @return
+   * @return array
    *   The array of extra fields.
    */
   public function getBundleExtraFields($entity_type, $bundle) {
@@ -560,13 +560,13 @@ public function getBundleExtraFields($entity_type, $bundle) {
   /**
    * Prepares a field definition for the current run-time context.
    *
-   * @param $field
+   * @param \Drupal\field\FieldInterface $field
    *   The raw field structure as read from the database.
    *
-   * @return
+   * @return \Drupal\field\FieldInterface
    *   The field definition completed for the current runtime context.
    */
-  public function prepareField($field) {
+  public function prepareField(FieldInterface $field) {
     // Make sure all expected field settings are present.
     $field['settings'] += $this->fieldTypeManager->getDefaultSettings($field['type']);
 
@@ -576,15 +576,15 @@ public function prepareField($field) {
   /**
    * Prepares an instance definition for the current run-time context.
    *
-   * @param $instance
+   * @param \Drupal\field\FieldInstanceInterface $instance
    *   The raw instance structure as read from the database.
-   * @param $field_type
+   * @param string $field_type
    *   The field type.
    *
-   * @return
+   * @return \Drupal\field\FieldInstanceInterface
    *   The field instance array completed for the current runtime context.
    */
-  public function prepareInstance($instance, $field_type) {
+  public function prepareInstance(FieldInstanceInterface $instance, $field_type) {
     // Make sure all expected instance settings are present.
     $instance['settings'] += $this->fieldTypeManager->getDefaultInstanceSettings($field_type);