Once I discovered this, I had to switch over my implementation to something less… of a legal risk. What a shame.
Looks like your standard software patent of an abstract idea so per https://en.wikipedia.org/wiki/Software_patents_under_United_... it is probably invalid. Also Oracle has issued a statement https://www.gordoni.com/software-patents/statements/oracle.s... in the 1990's saying that they oppose software patents, and besides the Android case with Google they seem to mainly be invalidating patents rather than suing others. So I would say the risk is minimal. But IANAL and to each their own.