Actually the licensing issues were from Linux developers' side - Oracle has nothing to say (as the license to the code and patents was given before Oracle got their grubby hands), and Sun IIRC expected CDDL to work similar to the AFS precedent where non-derivative, non-GPL code was allowed into kernel.

The only lawsuit specifically about licensing was from few Linux developers through SFC who disagree with common consensus on how GPL applies in that case and sued Ubuntu for shipping ZFS as a module.