Never mind, I found part of the answer inside ~/.m2/repository and realize that the BND instructions are placed as file names somehow, and not into a bnd file, so line breaks doesn't work.
Making it into a single line, the exception changes to
Caused by: java.net.MalformedURLException: Invalid syntax for instruction [Require-Capability: osgi.extender;filter:="(osgi.extender=osgi.serviceloader.processor)",osgi.serviceloader;filter:="(osgi.serviceloader=javax.json.spi.JsonProvider)";cardinality:=multiple]
Any thoughts?