Plantuml seems to be an old version?

[frankbenoit]

I am using a plantuml mindmap with multiple roots

[plantuml, "some", "png"]
----
@startmindmap
<style>
mindmapDiagram {
  .l1 {    BackgroundColor ivory      }
  .l2 {    BackgroundColor mintcream  }
}
</style>

' colors: see shades of white https://en.wikipedia.org/wiki/Alice_blue

* 1. Functional Suitability <<l1>>
** Functional correctness <<l2>>
***_ some other text

* 2. Maintainability <<l1>>
** topic <<l2>>
***_ other text

@endmindmap
----

I get this error:

"I don't know how to draw multi-root diagram. You should suggest an image so that the PlatUML team implements it :-)"

But the same file works fine in VS Code. Hence I think, that the used plantuml version used in eclipse-asciidoctor-editor is old.
Can you please update the used plantuml version?