NPE crash on malformed supplemental-model entry instead of clean error

[elharo]

Summary

getSupplement(Xpp3Dom) swallows XML parse errors and returns a null Model, and the caller then dereferences it unconditionally → NullPointerException instead of a clean error message.

src/main/java/org/apache/maven/plugin/resources/remote/AbstractProcessRemoteResourcesMojo.java:1008-1033

protected Model getSupplement(Xpp3Dom supplementModelXml) throws MojoExecutionException {
    ...
    try {
        model = modelReader.read(new StringReader(supplementModelXml.toString()));
        ...
    } catch (IOException e) {
        getLog().warn("Unable to read supplemental XML: " + e.getMessage(), e);
    } catch (XmlPullParserException e) {
        getLog().warn("Unable to parse supplemental XML: " + e.getMessage(), e);
    }
    return model;   // null when the inner <project> element is malformed
}

loadSupplements() then calls:

Model m = getSupplement(dom);
supplementMap.put(generateSupplementMapKey(m.getGroupId(), m.getArtifactId()), m);   // NPE if m == null

src/main/java/org/apache/maven/plugin/resources/remote/AbstractProcessRemoteResourcesMojo.java:1082-1083

Impact

A malformed <project> entry inside supplemental-models.xml (e.g. an invalid model element that MavenXpp3Reader rejects) crashes the build with an unhelpful NullPointerException rather than the intended warning/error path. Note the outer wrapper XML is parsed by SupplementalDataModelXpp3Reader in loadSupplements() and fails there cleanly; only the inner <project> DOM→Model conversion hits this path.

Suggested fix

throw a MojoExecutionException on parse failure instead of returning null.