How to get maven executable path from capability variable

[Alexandre Senecal]

I'm trying to get the path of the Maven executable as described here capability variable  but without success. My build agents use the executable label "Apache Maven 3.6.1".

I try to consume this variable in a script task. Tried passing it as an argument using the 

${bamboo.capability.<capability_key>}

syntax and in the script using the underscore syntax.

Please help