Support JVM packages on maven central

[rnett]

Is your feature request related to a problem? Please describe.
JVM packages are not supported at all.

Describe the solution you'd like
Support JVM packages (i.e. jars) on Maven Central.

Describe alternatives you've considered
N/A

Additional context
Domain ownership of the group ID is already validated by maven central, So ownership can either be done via that (i.e. requiring the MCP name match the group/artifact), or an attribute in the published POM.

[rnett]

FWIW I would expect JVM mcp servers to be typically ran via jbang, which lets you run published packages like npx does for JS.

[rdimitrov]

Good idea. Maven Central is a legitimate ecosystem worth covering, and the domain-ownership validation you mention is a nice natural fit. The process for adding a new package registry type is documented at docs/contributing/add-package-registry.md, and happy to review a PR. Tagging help wanted.