I want to create an empty set of Strings, as a starting point for further processing. (In this case, for generating a power set of some categories - which has to include the empty set)
Sounds like a simple task, right? But I'm actually quite stumped by this. What I've tried so far:
Table Creator: can only create simple values and smilies
GroupBy, Column Aggregator: When given only missing values, will either produce a missing value, too, or a set containing a missing value.
Java Snippet: Has the option to create arrays, but they are always interpreted as lists.
Missing Values: Seems only to be able to replace basic types
I tried that, but I can't produce a set that way, either, as both these Nodes only work with primitive types, again. But by now I found that a Table Creator (with a Dummy) followed by a Create Collection Column did the trick. I don't know why that Node would handle missing values differently than all the others, but what the hell, I'm glad it worked.
So... as far as I know, at least some of the places where I looked are extension points. Which means it should be easy to add an option to add empty collections... right?