diff --git a/core/modules/comment/src/Entity/Comment.php b/core/modules/comment/src/Entity/Comment.php
index 57c7287..c552d02 100644
--- a/core/modules/comment/src/Entity/Comment.php
+++ b/core/modules/comment/src/Entity/Comment.php
@@ -222,7 +222,8 @@ public static function baseFieldDefinitions(EntityTypeInterface $entity_type) {
 
     $fields['langcode'] = BaseFieldDefinition::create('language')
       ->setLabel(t('Language code'))
-      ->setDescription(t('The comment language code.'));
+      ->setDescription(t('The comment language code.'))
+      ->setRequired(TRUE);
 
     $fields['subject'] = BaseFieldDefinition::create('string')
       ->setLabel(t('Subject'))
@@ -272,23 +273,27 @@ public static function baseFieldDefinitions(EntityTypeInterface $entity_type) {
     $fields['created'] = BaseFieldDefinition::create('created')
       ->setLabel(t('Created'))
       ->setDescription(t('The time that the comment was created.'))
-      ->setTranslatable(TRUE);
+      ->setTranslatable(TRUE)
+      ->setRequired(TRUE);
 
     $fields['changed'] = BaseFieldDefinition::create('changed')
       ->setLabel(t('Changed'))
       ->setDescription(t('The time that the comment was last edited.'))
-      ->setTranslatable(TRUE);
+      ->setTranslatable(TRUE)
+      ->setRequired(TRUE);
 
     $fields['status'] = BaseFieldDefinition::create('boolean')
       ->setLabel(t('Publishing status'))
       ->setDescription(t('A boolean indicating whether the comment is published.'))
       ->setTranslatable(TRUE)
-      ->setDefaultValue(TRUE);
+      ->setDefaultValue(TRUE)
+      ->setRequired(TRUE);
 
     $fields['thread'] = BaseFieldDefinition::create('string')
       ->setLabel(t('Thread place'))
       ->setDescription(t("The alphadecimal representation of the comment's place in a thread, consisting of a base 36 string prefixed by an integer indicating its length."))
-      ->setSetting('max_length', 255);
+      ->setSetting('max_length', 255)
+      ->setRequired(TRUE);
 
     $fields['entity_type'] = BaseFieldDefinition::create('string')
       ->setLabel(t('Entity type'))
diff --git a/core/modules/node/src/Entity/Node.php b/core/modules/node/src/Entity/Node.php
index 4b7671f..a93d151 100644
--- a/core/modules/node/src/Entity/Node.php
+++ b/core/modules/node/src/Entity/Node.php
@@ -349,7 +349,8 @@ public static function baseFieldDefinitions(EntityTypeInterface $entity_type) {
     $fields['langcode'] = BaseFieldDefinition::create('language')
       ->setLabel(t('Language code'))
       ->setDescription(t('The node language code.'))
-      ->setRevisionable(TRUE);
+      ->setRevisionable(TRUE)
+      ->setRequired(TRUE);
 
     $fields['title'] = BaseFieldDefinition::create('string')
       ->setLabel(t('Title'))
@@ -400,7 +401,8 @@ public static function baseFieldDefinitions(EntityTypeInterface $entity_type) {
       ->setDescription(t('A boolean indicating whether the node is published.'))
       ->setRevisionable(TRUE)
       ->setTranslatable(TRUE)
-      ->setDefaultValue(TRUE);
+      ->setDefaultValue(TRUE)
+      ->setRequired(TRUE);
 
     $fields['created'] = BaseFieldDefinition::create('created')
       ->setLabel(t('Authored on'))
@@ -416,13 +418,15 @@ public static function baseFieldDefinitions(EntityTypeInterface $entity_type) {
         'type' => 'datetime_timestamp',
         'weight' => 10,
       ))
-      ->setDisplayConfigurable('form', TRUE);
+      ->setDisplayConfigurable('form', TRUE)
+      ->setRequired(TRUE);
 
     $fields['changed'] = BaseFieldDefinition::create('changed')
       ->setLabel(t('Changed'))
       ->setDescription(t('The time that the node was last edited.'))
       ->setRevisionable(TRUE)
-      ->setTranslatable(TRUE);
+      ->setTranslatable(TRUE)
+      ->setRequired(TRUE);
 
     $fields['promote'] = BaseFieldDefinition::create('boolean')
       ->setLabel(t('Promote'))
@@ -437,7 +441,8 @@ public static function baseFieldDefinitions(EntityTypeInterface $entity_type) {
         ),
         'weight' => 15,
       ))
-      ->setDisplayConfigurable('form', TRUE);
+      ->setDisplayConfigurable('form', TRUE)
+      ->setRequired(TRUE);
 
     $fields['sticky'] = BaseFieldDefinition::create('boolean')
       ->setLabel(t('Sticky'))
@@ -451,7 +456,8 @@ public static function baseFieldDefinitions(EntityTypeInterface $entity_type) {
         ),
         'weight' => 16,
       ))
-      ->setDisplayConfigurable('form', TRUE);
+      ->setDisplayConfigurable('form', TRUE)
+      ->setRequired(TRUE);
 
     $fields['revision_timestamp'] = BaseFieldDefinition::create('created')
       ->setLabel(t('Revision timestamp'))
diff --git a/core/modules/node/src/NodeStorageSchema.php b/core/modules/node/src/NodeStorageSchema.php
index 4d02d3b..f816aac 100644
--- a/core/modules/node/src/NodeStorageSchema.php
+++ b/core/modules/node/src/NodeStorageSchema.php
@@ -68,6 +68,7 @@ protected function getSharedTableFieldSchema(FieldStorageDefinitionInterface $st
         case 'title':
           // Improves the performance of the indexes defined
           // in getEntitySchema().
+          // @todo: Autogenerate.
           $schema['fields'][$field_name]['not null'] = TRUE;
           break;
 
diff --git a/core/modules/taxonomy/src/Entity/Term.php b/core/modules/taxonomy/src/Entity/Term.php
index caebc53..54c76f2 100644
--- a/core/modules/taxonomy/src/Entity/Term.php
+++ b/core/modules/taxonomy/src/Entity/Term.php
@@ -157,7 +157,8 @@ public static function baseFieldDefinitions(EntityTypeInterface $entity_type) {
     $fields['weight'] = BaseFieldDefinition::create('integer')
       ->setLabel(t('Weight'))
       ->setDescription(t('The weight of this term in relation to other terms.'))
-      ->setDefaultValue(0);
+      ->setDefaultValue(0)
+      ->setRequired(TRUE);
 
     $fields['parent'] = BaseFieldDefinition::create('entity_reference')
       ->setLabel(t('Term Parents'))
diff --git a/core/modules/taxonomy/src/TermStorageSchema.php b/core/modules/taxonomy/src/TermStorageSchema.php
index 9923288..76d33d7 100644
--- a/core/modules/taxonomy/src/TermStorageSchema.php
+++ b/core/modules/taxonomy/src/TermStorageSchema.php
@@ -129,6 +129,7 @@ protected function getSharedTableFieldSchema(FieldStorageDefinitionInterface $st
         case 'weight':
           // Improves the performance of the taxonomy_term__tree index defined
           // in getEntitySchema().
+          // @todo: Auto-generate.
           $schema['fields'][$field_name]['not null'] = TRUE;
           break;
 
diff --git a/core/modules/user/src/Entity/User.php b/core/modules/user/src/Entity/User.php
index 629ce9c..d401eb8 100644
--- a/core/modules/user/src/Entity/User.php
+++ b/core/modules/user/src/Entity/User.php
@@ -453,7 +453,8 @@ public static function baseFieldDefinitions(EntityTypeInterface $entity_type) {
 
     $fields['langcode'] = BaseFieldDefinition::create('language')
       ->setLabel(t('Language code'))
-      ->setDescription(t('The user language code.'));
+      ->setDescription(t('The user language code.'))
+      ->setRequired(TRUE);
 
     $fields['preferred_langcode'] = BaseFieldDefinition::create('language')
       ->setLabel(t('Preferred language code'))
@@ -475,7 +476,8 @@ public static function baseFieldDefinitions(EntityTypeInterface $entity_type) {
         // that.
         'UserName' => array(),
         'UserNameUnique' => array(),
-      ));
+      ))
+      ->setRequired(TRUE);
 
     $fields['pass'] = BaseFieldDefinition::create('string')
       ->setLabel(t('Password'))
@@ -504,25 +506,30 @@ public static function baseFieldDefinitions(EntityTypeInterface $entity_type) {
     $fields['status'] = BaseFieldDefinition::create('boolean')
       ->setLabel(t('User status'))
       ->setDescription(t('Whether the user is active or blocked.'))
-      ->setDefaultValue(FALSE);
+      ->setDefaultValue(FALSE)
+      ->setRequired(TRUE);
 
     $fields['created'] = BaseFieldDefinition::create('created')
       ->setLabel(t('Created'))
-      ->setDescription(t('The time that the user was created.'));
+      ->setDescription(t('The time that the user was created.'))
+      ->setRequired(TRUE);
 
     $fields['changed'] = BaseFieldDefinition::create('changed')
       ->setLabel(t('Changed'))
-      ->setDescription(t('The time that the user was last edited.'));
+      ->setDescription(t('The time that the user was last edited.'))
+      ->setRequired(TRUE);
 
     $fields['access'] = BaseFieldDefinition::create('timestamp')
       ->setLabel(t('Last access'))
       ->setDescription(t('The time that the user last accessed the site.'))
-      ->setDefaultValue(0);
+      ->setDefaultValue(0)
+      ->setRequired(TRUE);
 
     $fields['login'] = BaseFieldDefinition::create('timestamp')
       ->setLabel(t('Last login'))
       ->setDescription(t('The time that the user last logged in.'))
-      ->setDefaultValue(0);
+      ->setDefaultValue(0)
+      ->setRequired(TRUE);
 
     $fields['init'] = BaseFieldDefinition::create('email')
       ->setLabel(t('Initial email'))
diff --git a/core/modules/user/src/UserStorageSchema.php b/core/modules/user/src/UserStorageSchema.php
index 447469d..7ef0f66 100644
--- a/core/modules/user/src/UserStorageSchema.php
+++ b/core/modules/user/src/UserStorageSchema.php
@@ -51,6 +51,7 @@ protected function getSharedTableFieldSchema(FieldStorageDefinitionInterface $st
         case 'name':
           // Improves the performance of the user__name index defined
           // in getEntitySchema().
+          // @todo: Auto-generate.
           $schema['fields'][$field_name]['not null'] = TRUE;
           break;
 
diff --git a/sites/default/default.settings.php b/sites/default/default.settings.php
index 36385f7..cc2eb32 100644
--- a/sites/default/default.settings.php
+++ b/sites/default/default.settings.php
@@ -414,6 +414,14 @@
 # $settings['allow_authorize_operations'] = FALSE;
 
 /**
+ * Mixed-mode sessions:
+ *
+ * Set to TRUE to create both secure and insecure sessions when using HTTPS.
+ * Defaults to FALSE.
+ */
+# $settings['mixed_mode_sessions'] = TRUE;
+
+/**
  * Default mode for for directories and files written by Drupal.
  *
  * Value should be in PHP Octal Notation, with leading zero.
@@ -431,18 +439,6 @@
 # $settings['file_public_path'] = 'sites/default/files';
 
 /**
- * Private file path:
- *
- * A local file system path where private files will be stored. This directory
- * must be absolute, outside of the the Drupal installation directory and not
- * accessible over the web.
- *
- * See http://drupal.org/documentation/modules/file for more information about
- * securing private files.
- */
-# $settings['file_private_path'] = '';
-
-/**
  * Session write interval:
  *
  * Set the minimum interval between each session write to database.