There doesn't seem to be a way to define this currently: https://www.uml-diagrams.org/realization.html
PlantUML calls it lollipop: https://plantuml.com/class-diagram and supports it like this:
bar ()- foo
bar ()-- foo
foo -() bar
I will start work on this after January 6th. Unless someone else is interested :)
@jgreywolf I think this will be resolved by PR #1171 as that adds supports for dashed lines. After this PR the following relations will be available.

I think that resolves part of it. The other part was being able to do something like the following:

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I think that resolves part of it. The other part was being able to do something like the following: