"gradle javadoc" command ignores changes in "package.html" files

“gradle javadoc” command ignores changes in “package.html” files.

(tried with Gradle 2.2.1, 2.3)

if I edit package.html file in the project folder (this file is used for package-level javadocs), running “gradle javadoc” shows:

$ gradle javadoc :compileJava UP-TO-DATE :processResources UP-TO-DATE :classes UP-TO-DATE :javadoc UP-TO-DATE

then I open the generated index.html file and see old content there.