After the SB 3.1.6 -> 3.1.7 update we started to have an issue with docker-java library connecting to docker daemon:

org.apache.hc.client5.http.HttpHostConnectException: Connect to unix://localhost:2375 [localhost/127.0.0.1, localhost/0:0:0:0:0:0:0:1] failed: Connection refused.

We haven't changed any configuration, we've been always using UNIX socket at /var/run/docker.sock.

Downgrading to 3.1.6 solved the issue.

Could also be due to an update of an external dependency.

More details:
docker-java/docker-java#2290