Change record status: 
Project: 
Introduced in branch: 
8.5.x
Introduced in version: 
8.5.0
Description: 

The global constants in datetime.module are deprecated, and replaced by constants on a new interface, Drupal\datetime\Plugin\Field\FieldType\DateTimeItemInterface

Instead of DATETIME_STORAGE_TIMEZONE, use \Drupal\datetime\Plugin\Field\FieldType\DateTimeItemInterface::STORAGE_TIMEZONE instead.

Instead of DATETIME_DATETIME_STORAGE_FORMAT, use \Drupal\datetime\Plugin\Field\FieldType\DateTimeItemInterface::DATETIME_STORAGE_FORMAT instead.

Instead of DATETIME_DATE_STORAGE_FORMAT, use \Drupal\datetime\Plugin\Field\FieldType\DateTimeItemInterface::DATE_STORAGE_FORMAT instead.

Impacts: 
Module developers
Updates Done (doc team, etc.)
Online documentation: 
Not done
Theming guide: 
Not done
Module developer documentation: 
Not done
Examples project: 
Not done
Coder Review: 
Not done
Coder Upgrade: 
Not done
Other: 
Other updates done