prometheus-metrics-shaded-protobuf OSGi support missing

[croister]

I tried stepping to the 1.3.1 version of Prometheus Metrics from the 0.16.0 Prometheus SimpleClient version in a OSGi environment (Apache Karaf 4.4.6).
The "prometheus-metrics-shaded-protobuf" bundle does not start as expected, instead this error is thrown:

[INFO] Suppressed: java.lang.Exception: Unable to create resource for bundle mvn:io.prometheus/prometheus-metrics-shaded-protobuf/1.3.1
<...>
Caused by: org.osgi.framework.BundleException: Unable to build resource for mvn:io.prometheus/prometheus-metrics-shaded-protobuf/1.3.1: Unsupported 'Bundle-ManifestVersion' value: 1

This is caused by the fact that the original MANIFEST.MF file is excluded when the shaded jar is created.
That file contains the OSGi data that is needed for OSGi support.
It seems to fall back to version '1' of 'Bundle-ManifestVersion' when no information is found in the file.

To solve the issue the metadata needs to be kept in the new shaded jar file and maybe changed to the new group id/paths.
Either copy over the contents and replace paths or maybe even add the karaf-maven-plugin and generate new metadata.