public Builder<T> editableGroup(Boolean editableGroup) {
            event.setEditableGroup(editableGroup);
            return this;
        }
The type of the item. Can be 'box' (default), 'point', 'range', or 'background'.
<p>
Types 'box' and 'point' need a start date, the types 'range' and 'background' needs both a start and end date.
primefaces/src/main/java/org/primefaces/model/timeline/TimelineEvent.java