That is easy to disprove. If CDDL did not care, then one could follow the conditions in GPLv2 and the two licenses would be compatible.<p>License incompatibility can <i>only</i> occur if two license has <i>conditions</i> which are <i>mutually</i> exclusive. In this case, CDDL demands that source code must be distributed only under the terms of CDDL, and GPLv2 require that the distributed source code is made available under GPLv2. You can not comply with one without breaking the other, and thus we have license incompatibility.