Maven classifier is being mangled

I have a maven module publishing snapshots releases to GitHub Packages.

The module contains a regular jar and multiple architecture-specific jars which is being indicated by classifiers:

native-1.1.0-SNAPSHOT.jar
native-1.1.0-SNAPSHOT-windows-x86_64.jar
native-1.1.0-SNAPSHOT-linux-x86_64.jar
native-1.1.0-SNAPSHOT-osx-x86_64.jar

The maven metadata generated after publishing those artifacts is invalid, which makes it impossible to download artifacts with classifiers.

For example, this is the metadata for the artifact with the osx-x86_64 classifier:

<snapshotVersion>
  <extension>x86_64.jar</extension>
  <classifier>osx</classifier>
  <value>1.1.0-20201116.020343-2</value>
  <updated>20201116020345</updated>
</snapshotVersion>

The classifier gets truncated after the first dash and the rest of the classifier spills over into the extension tag. Valid metadata in this case would be:

<snapshotVersion>
  <extension>jar</extension>
  <classifier>osx-x86_64</classifier>
  <value>1.1.0-20201116.020343-2</value>
  <updated>20201116020345</updated>
</snapshotVersion>

The metadata created by github packages would only be valid if there was a dot after “osx”, making the file extension x86_64.jar. But there is no dot in the files i’m uploading, only a dash.