When you run a PageRankVertexProgram or a PeerPressureVertexProgram, you have an edgeCount property which is used for determining the weight distribution. This is just some "scratch pad data." We need a way to tell the GraphComputer which properties are "scratch pad" and thus, delete them before outputting the `ComputerResult`.
We can have a default that returns Collections.emptySet(). This would be breaking as the GraphComputer provider will need to handle dropping such properties. This, of course, will be verified in a GraphComputerTest.shouldSupportTransientProperties().