Convert Strings to String Collections, and Vice Versa
Some input parameters requires strings in one of two forms. Send Rich Email, for example, can take a list of string email addresses but can’t (currently) take a comma-separated-list.
This package provides a set of simple actions to convert data from one form to the other.

Convert from Collection to CSV String
This takes a string collection and returns a csv string.
Convert To String Collection
ConvertToStringCollection, can use a provided character as a delimiter. For example, if you pass in the output of a multiselect picklist and set the delimiter to a semicolon, you’ll convert multiselect picklist output to a collection of strings that can be worked on later in the flow.
Install
4/16/23 Version 1.2 Production Sandbox Categorized as Utilities; You can pass in an alternative delimiter to comma.
Old Versions