Embracing the power of the empty set in API design

That's a good one: common API design is:

/resources - return all resources

/resources?type=a&type=b (or type=a,b) - return resources of given type.

Then suddenly UI team implements checkbox-based deletion (or bulk edit). User deselects all checkboxes, and UI sends DELETE `/resources` (or `?type=`), suddenly deletes all resources.