Plantuml marks these empty items as an error when there is not at least a new line.
I have only tried for class diagram items, unsure if same applies to other items.
All of the below fail:
package foo {}
namespace bar {}
class qux {}
Whereas all of the following are valid
package foo {
}
namespace bar {
}
class qux {
}
FWIW, I wouldn't expect any requirement on an empty element, especially white-space requirement .
Took me a while to figure out why I was seeing an error!