That is a really good question, which I do not know the answer to, but I'd like to know as well.
To add to that here are a few other examples which Jeanne did not supply, but I think they do apply to this topic:It's been my experience that you if use a variable then you need to use the double quote as shown below:From looking at the documentation/examples provided by Gradle it appears as though usually (but not always) single quotes/apostrophes is used as opposed to the double quotes.
Plus, fairly often (but not always) in the documentation/examples they use this type of notation when dealing with plugins:All of the preceding examples different notations then what Jeanne provided in her initial post.
I wonder if some of this ambiguity is related to Groovy of is it all related to Gradle?
“The strongest of all warriors are these two — Time and Patience.” ― Leo Tolstoy, War and Peace
I'm at a Groovy presentation at DevNexus. Ken Kousen (who wrote a book about Java) showed the 'group:name:version' syntax and said he likes it better. But he said either is fine. So I think it is a personal preference thing.