Missing license info for io.prometheus packages in Maven Central #2216

Hi,

we attempted to upgrade to newer versions of Prometheus packages from Maven Central / Apache's Maven Repository, but several of the packages are failing our automated legal compliance processes. The cause for this seems to be that the source JAR files seem to be missing any kind of license files.

The affected components are:
https://repo.maven.apache.org/maven2/io/prometheus/prometheus-metrics-exposition-textformats/1.5.1/prometheus-metrics-exposition-textformats-1.5.1-sources.jar
https://repo.maven.apache.org/maven2/io/prometheus/prometheus-metrics-model/1.5.1/prometheus-metrics-model-1.5.1-sources.jar
https://repo.maven.apache.org/maven2/io/prometheus/prometheus-metrics-config/1.5.1/prometheus-metrics-config-1.5.1-sources.jar
https://repo.maven.apache.org/maven2/io/prometheus/prometheus-metrics-tracer-common/1.5.1/prometheus-metrics-tracer-common-1.5.1-sources.jar
https://repo.maven.apache.org/maven2/io/prometheus/prometheus-metrics-config/1.7.0/prometheus-metrics-config-1.7.0-sources.jar
https://repo.maven.apache.org/maven2/io/prometheus/prometheus-metrics-exposition-textformats/1.7.0/prometheus-metrics-exposition-textformats-1.7.0-sources.jar
https://repo.maven.apache.org/maven2/io/prometheus/prometheus-metrics-model/1.7.0/prometheus-metrics-model-1.7.0-sources.jar