Update outdated Gradle plugin documentation regarding source files

[Marcono1234]

Fixes #3781

[cortinico]

Thank you for the fix 🙏

[codecov]

Codecov Report

Merging #3883 (ea4541f) into main (85533a0) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##               main    #3883   +/-   ##
=========================================
  Coverage     83.50%   83.50%           
  Complexity     3117     3117           
=========================================
  Files           456      456           
  Lines          9002     9002           
  Branches       1758     1758           
=========================================
  Hits           7517     7517           
  Misses          566      566           
  Partials        919      919           

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