Allow bundle parameters to be a string

[Lakitna]

Is your feature request related to a problem? Please describe.
In simple situations, it would be nice if instead of an object a short string could be provided.

Describe the solution you'd like
Instead of requiring bundle parameters to be an object, also allow a string.

Describe alternatives you've considered
A default parameters key, but that's not a very clean solution.

[Lakitna]

Part of next release