The certification matrix is the reference document, support can't "override" (reducing) the certification matrix without correcting the matrix available. Ideally support can only extend the certification matrix by affirming that something newer not listed is also officially supported (like Informatica 10.2 while the matrix only talk about 10.1).

If the certification says JDK 1.8, that's it (also because having to go back to a JDK 1.6 sounds quite risky ... end of updates for that 1.6 was in 2013 or there around).