Iterating through project files causes long configuration phase times

[cvb941]

This is the line in question:

ResourcePlaceholdersPlugin/plugin/src/main/kotlin/de/timfreiheit/plugin/resourceplaceholders/ResourcePlaceholdersPlugin.kt

Line 82 in a110cd3

return project.layout.projectDirectory.asFileTree.filter {

I had a lot of files in my project, so much that the Gradle configuration phase took 1m30s to complete, simply by iterating through these files in that step.