How to create a Custom Field calculated in JIRA with JIRA MISC addon – www.MrAddon.com ®: Jira & Confluence Administration Support Blog & Ethereum Dev Blog – [www.MrAddon.blog] ®
Managing custom fields | Administering Jira applications Data Center and Server 8.17 | Atlassian Documentation
Custom Fields ++ for Jira | Atlassian Marketplace
Create custom fields - Extension for Jira Service Management