Intellij plugin - Action menu is empty and show "Nothing here"

I'm trying to create menu actions upon clicking on a gutter icon.

I'm working with the following example, RunLineMarkerProvider.java

https://github.com/JetBrains/intellij-community/blob/d5e5bdf21650d9bf6e3bc36e26307c1f7098b251/platform/execution-impl/src/com/intellij/execution/lineMarker/RunLineMarkerProvider.java

Looks like this is the way to add an action menu, but I see "Nothing here" instead of  actions, how should I fix that?

Running on:

IntelliJ IDEA 2019.2.4 (Ultimate Edition)

Plugin SDK: IntelliJ IDEA IU-192.7142.36

Thanks,

Hagai