Why does Gradle call getInputFiles() twice?

Hello,

I’m trying to improve a plugin that I wrote a while back. I implemented getInputFiles() and I’m surprised to see that it’s called twice. I discovered getInputFiles from looking at someone else’s extension. When I went looking for it in the Gradle API docs, I wasn’t able to find it.

Can someone point me to where it’s documented and/or explain when/why it’s called?