Inconsistent resource-bundle descriptor parsing between validate() and downloadBundles()

[elharo]

Summary

The bundle descriptor is validated with StringUtils.split (which collapses empty segments) but parsed later with String.split(":") (which preserves them), so certain malformed descriptors pass validation and then fail confusingly during resolution.

src/main/java/org/apache/maven/plugin/resources/remote/AbstractProcessRemoteResourcesMojo.java

• validate(): StringUtils.split(artifactDescriptor, ":") — line 728, empty tokens removed, so group:artifact::type counts as 3 tokens and passes the length check (3..5).
• downloadBundles(): artifactDescriptor.split(":") — line 822, empty tokens kept, so group:artifact::type yields [group, artifact, "", type] and resolution proceeds with an empty version.

Impact

A descriptor such as group:artifact::type (missing version) passes validate() with a clear message never shown, then fails later with a confusing version/resolution error. Also in the reactor lookup, s[0].equals(p.getGroupId()) can throw if p.getGroupId() is null.

Suggested fix

Use the same splitting logic in both methods (and ideally a single parser that also checks that groupId/artifactId/version are non-empty), and null-guard the reactor comparison.