Empty build rather than delete for Eclipse derived?

[Jacques Le Roux]

Hi,

I recently suggested that to no be encumbered with Gradle build and bin folder in Eclipse you can set them as derived (folder attribute in its 
properties).

This works well for bin, but, each time we do a clean, the build folder loses 
its attributes because it's deleted and regenerated.

Could we not empty it rather than delete?

Thanks

Jacques