Bump to Checker dataflow 3.20.0 (#510)
Bump to Checker dataflow 3.20.0 (#510)

The key new feature here is that the dataflow library no longer crashes on switch expressions / arrow case labels in switch statements:

https://github.com/typetools/checker-framework/blob/checker-framework-3.20.0/docs/CHANGELOG.md#version-3200-december-6-2021

This is an initial step toward fixing #289, though we will need precise control-flow graphs (which is still a WIP in Checker dataflow) to really handle these constructs properly.
uber/nullaway,uber/nullaway,uber/nullaway