I cant set script parameters and properties with spaces correctly.

I have a step "Execute Groovy script" with the command:
println System.getProperty("param")

Double qoutes
The script parameters: -Dparam="a b"
The Properties: param="a b"

Both print: null

Single qoutes
The script parameters: -Dparam='a b'
prints: null

The Properties: param='a b'
prints: 'a b'
The string contains the single qoutes

My workaround is to use properties with single qoutes and remove them within the script.