diff --git a/core/modules/field/lib/Drupal/field/Plugin/Core/Entity/Field.php b/core/modules/field/lib/Drupal/field/Plugin/Core/Entity/Field.php
index e7e9bd5..3692de2 100644
--- a/core/modules/field/lib/Drupal/field/Plugin/Core/Entity/Field.php
+++ b/core/modules/field/lib/Drupal/field/Plugin/Core/Entity/Field.php
@@ -210,7 +210,22 @@ class Field extends ConfigEntityBase implements FieldInterface {
   protected $storageDetails;
 
   /**
-   * {@inheritdoc}
+   * Constructs a Field object.
+   *
+   * @param array $values
+   *   An array of field properties, keyed by property name. Most array elements
+   *   will be used to set the corresponding properties on the class; see the
+   *   class property documentation for details. Some array elements have special
+   *   meanings and a few are required; these special elements are:
+   *   - id: required. As a temporary Backwards Compatibility layer right now,
+   *     a 'field_name' property can be accepted in place of 'id'.
+   *   - type: required.
+   * 
+   * In most cases, it's constructed via entity_create('field_entity', $values)), where
+   * $values is the same parameter for this constructor.
+   *
+   * See: @link entity_create() @endlink.
+   * @ingroup field Field API data structures
    */
   public function __construct(array $values, $entity_type = 'field_entity') {
     // Check required properties.
diff --git a/core/modules/field/lib/Drupal/field/Plugin/Core/Entity/FieldInstance.php b/core/modules/field/lib/Drupal/field/Plugin/Core/Entity/FieldInstance.php
index 66d8cbf..b73eae8 100644
--- a/core/modules/field/lib/Drupal/field/Plugin/Core/Entity/FieldInstance.php
+++ b/core/modules/field/lib/Drupal/field/Plugin/Core/Entity/FieldInstance.php
@@ -201,7 +201,24 @@ class FieldInstance extends ConfigEntityBase implements FieldInstanceInterface {
   protected $bundle_rename_allowed = FALSE;
 
   /**
-   * {@inheritdoc}
+   * Constructs a FieldInstance object.
+   *
+   * @param array $values
+   *   An array of field instance properties, keyed by property name. Most array
+   *   elements will be used to set the corresponding properties on the class; see
+   *   the class property documentation for details. Some array elements have
+   *   special meanings and a few are required; these special elements are:
+   *   - field_name: optional. The name of the field this is an instance of.
+   *   - field_uuid: optional. Either field_uuid or field_name is required
+   *     to build field instance. field_name will gain higher priority.
+   *     If field_name is not provided, field_uuid will be checked then.
+   *   - entity_type: required.
+   *   - bundle: required.
+   *
+   * In most cases, it's constructed via entity_create('field_instance', $values)), where
+   * $values is the same parameter for this constructor.
+   *
+   * See: @link entity_create() @endlink.
    */
   public function __construct(array $values, $entity_type = 'field_instance') {
     // Accept incoming 'field_name' instead of 'field_uuid', for easier DX on