Sitemap filename can't exceed 32 characters issue #13937 fixed.

[irajneeshgupta]

Description (*)

The Sitemap filename length validation was not added , hence added \Magento\Framework\Validator\StringLength max 32 length validation for sitemap filename and it will not trim filename exceeding 32 chars.

Fixed Issues (if relevant)

1. magento/magento2#Sitemap filename can't exceed 32 characters magento/magento2#13937: Issue title : Sitemap filename can't exceed 32 characters

Contribution checklist (*)

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All new or changed code is covered with unit/integration tests (if applicable)
• All automated tests passed successfully (all builds on Travis CI are green)