Hide the method that allows setting probability for particular edge and introduce a public method that sets probabilities for all outgoing edges at once.
Setting individual edge probability is error prone. More over it is difficult to check that the total probability is 1.0 because there is no easy way to know when the user finished setting all the probabilities.
One bug is fixed in BranchProbabilityInfo::calcMetadataWeights(). Changing unreachable branch probabilities to raw(1) and distributing the rest (oldProbability - raw(1)) over the reachable branches could introduce total probability inaccuracy bigger than 1/numOfBranches.