Issue #2149877 by amateescu, swentel: The 'filesize' base field of field entities is a boolean?.

core/modules/file/lib/Drupal/file/Entity/File.php

@@ -247,8 +247,7 @@ public static function baseFieldDefinitions($entity_type) {
       ->setLabel(t('File MIME type'))
       ->setDescription(t("The file's MIME type."));
 
-    // @todo Convert to an integer field in https://drupal.org/node/2149877.
-    $fields['filesize'] = FieldDefinition::create('boolean')
+    $fields['filesize'] = FieldDefinition::create('integer')
       ->setLabel(t('File size'))
       ->setDescription(t('The size of the file in bytes.'));