Hi,
it was me who contacted ozwald and asked about legality of that particular HDRI. I got an answer that HDRI was resized, but there was no mentioning about free sample, so i had to take the link down (topic itself was deleted by ozwald's request). If i would be told that HDRI was from free sample, it would be enough to mention from where HDRI was obtained and maybe provide some simple licence text.
Anyway, as i said to ozwald already, if you have material that you can't share publicly, you can always pack your scene and ypload to Corona's private uploader - only Team members will have access to it and they will use it for problem identification purpose only.