We have switched to using only Java's implementation of BigInteger and BigDecimal. However, we still have some lingering usages of Scala's version.
We can find such uses by using the dissasembler:
javap -c -l `find . -name *.class | grep scala-2.12` > src.bytecode
Then searching the resulting file for "scala/math/BigInt" and "scala/math/BigDecimal"
Since all our tests pass, these appear to not cause any functional issue, but should be cleaned up for purposes of consistency.