Use case
Return the lowest date from a Date Time 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:
%{count(fieldValue({issue.cfnnnnn},linkedIssues()))> 0 dateTimeToString(min(fieldValue({issue.cfnnnnn},linkedIssues())),RUN_AS_LOCAL,RUN_AS_LANG):""}
Please, replace nnnnn with the ID of a Date Time Picker custom field.
