When accessing an address
http://localhost:8080/business-central/rest
I get an ugly exception:

FAILURE /business-central/rest Could not find resource for relative : /business-central/rest of full path: http://localhost:8080/business-central/rest org.jboss.resteasy.spi.NotFoundException: Could not find resource for relative : /business-central/rest of full path: http://localhost:8080/business-central/rest at org.jboss.resteasy.core.registry.RootSegment.matchChildren(RootSegment.java:360) at
...

The root of the REST API and perhaps other REST API incomplete URLs should rather offer a basic navigation and list of available commands like in this wiki:
https://github.com/mrietveld/droolsjbpm-integration/wiki/Rest-API

BRMS 5.3.x business central REST API was able to offer a basic help, so this can be considered a regression.