R version. 3.1.x is too old. It's released 4.5 years ago.
R 3.4.0 is released 1.5 years ago. Considering the timing for Spark 3.0, deprecating lower versions, bumping up R to 3.4 might be reasonable option.
It should be good to deprecate and drop < R 3.4 support.
If we think about the practice, nothing particular is required within R codes as far as I can tell.
We will just upgrade Jenkins's R version to 3.4, which mean we're not going to test 3.1 R version (but instead we will test 3.4).