Use case
Return the lowest date from a Date Picker custom field in the linked issues of the current issue.
Expression
Create and configure a Smart field using this expression in General parsing mode:
%{jiraExpression("let minDate = '" + dateToString(min(filterByValue(fieldValue({issue.cfnnnnn}, linkedIssues()), != , null)), RUN_AS_LOCAL, RUN_AS_LANG) + "'; minDate == 'Invalid date' ? null : minDate")}
Please, replace nnnnn with the ID of a Date Picker custom field.
