diff --git a/core/lib/Drupal/Core/Field/FieldItemInterface.php b/core/lib/Drupal/Core/Field/FieldItemInterface.php
index 64e7012..b9154db 100644
--- a/core/lib/Drupal/Core/Field/FieldItemInterface.php
+++ b/core/lib/Drupal/Core/Field/FieldItemInterface.php
@@ -26,9 +26,11 @@
   /**
    * Returns the schema for the field.
    *
-   * This method is static, because the field schema information is needed on
-   * creation of the field. No field instances exist by then, and it is not
-   * possible to instantiate a FieldItemInterface object yet.
+   * This method is static because the field schema information is needed on
+   * creation of the field. FieldItemInterface objects instantiated at that
+   * time are not reliable as field instance settings might be missing.
+   *
+   * Computed fields should return an empty array.
    *
    * @param \Drupal\Core\Field\FieldDefinitionInterface $field_definition
    *   The field definition.