In Java you would call,
final InSARStackOverview.IfgStack[] stackOverview = InSARStackOverview.calculateInSAROverview(product);
final InSARStackOverview.IfgPair[] slaves = stackOverview[0].getMasterSlave();
and then you can get the baselines.
From GPT you can’t at the moment but it’s on the list to add baseline information to the product metadata.