A proposal for supporting "groups" in DAP output events:

A new optional enum property group is added to the Output event with these values:

• start: start a new group in expanded mode. Subsequent Output events are members of the group and should be shown indented. The output attribute becomes the name of the group and is not indented.
• startCollapsed: start a new group in collapsed mode. Subsequent Output events are members of the group and should be shown indented (as soon as the group is expanded). The output attribute becomes the name of the group and is not indented.
• end: end the current group and decreases the indentation of subsequent Output events. A non empty output attribute is shown as the unindented end of the group.

See microsoft/vscode#34981