Looks like we stopped copying LICENSE and NOTICE files to the root of the assembly. 3.1.1 has it. But 4.0.M3 doesn't. Source version of the release has it, but buried many levels deep. And jar files have it under META-INF/cayenne.
Somehow that got overlooked when we voted on M3. I guess this means it's time for M4.... I am going to fix the issue on master now. Andrus
