maven-args where the value of an argument contains a space

[sitepark-veltrup]

I want to use maven-args to set the argument -DpreparationGoals with multiple goals separated by a space.

-DpreparationGoals=clean my:goal verify

But I can't find a way to specify this. I have tried the following variants:

maven-args: '-DpreparationGoals="clean my:goal verify"'
maven-args: "-DpreparationGoals='clean my:goal verify'"
maven-args: '-DpreparationGoals="clean my:goal verify"'
maven-args: '-DpreparationGoals=clean\ my:goal\ verify'

The release fails with messages such as:

Could not find goal 'goal\'

Could not find goal 'verify"'

Could not find goal 'verify''

How should I specify the argument?