How to organize a Gantt chart with specific EPICs and their child issues

Question: I would like to be able to select specific epics to create the wbs gantt-chart with all their children issues

Answer: You can create a filter that contains all the epics you want to display on the Gantt Chart, and then create a Gantt Chart from that filter. However, Subtasks are excluded because subtask Issue Type doesn’t have Epic link. To include the subtasks in the filter result you need to install other plugin such as ScriptRunner for Jira (linkedIssuesOfRecursive),