Interpolation of embedded arrays does not work

If a configuration property is already a string array, and at least one of the values contains a placeholder which gets replaced with an array, then the resulting array should contain these array values as separate values.
Right now, the array value will be a string array.
For example:
property=[ "1000", "$[prop:foo;type=String[];delimiter=,]", "4000"]
with foo="2000,3000"
should result in ["1000", "2000", "3000", "4000"]
Right now it results in
["1000", ["2000", "3000"], "4000"]