copyProperties throws NPE on dependencies with no resolved artifact file

[elharo]

Summary

AntRunMojo.copyProperties(MavenProject, Project) dereferences artifact.getFile() without a null check when registering the per-dependency artifact properties. Any project dependency whose artifact has no resolved file crashes the mojo with an opaque NullPointerException instead of a clear resolution error.

Affected code

src/main/java/org/apache/maven/plugins/antrun/AntRunMojo.java lines 430-436 (master @ 441382c)

Set<Artifact> depArtifacts = mavenProject.getArtifacts();
for (Artifact artifact : depArtifacts) {
    String propName = artifact.getDependencyConflictId();
    antProject.setProperty(propertyPrefix + propName, artifact.getFile().getPath());
}

Problem

artifact.getFile() may be null (e.g. partial/offline resolution, or dependencies whose artifact file was never downloaded), and the code calls .getPath() on it directly. The same class already handles this case consistently in getPathFromArtifacts (AntRunMojo.java:362-381), which throws a DependencyResolutionRequiredException when artifact.getFile() == null:

for (Artifact a : artifacts) {
    File file = a.getFile();
    if (file == null) {
        throw new DependencyResolutionRequiredException(a);
    }
    list.add(file.getPath());
}

Expected behavior

Dependency artifacts with no resolved file should be skipped or reported with a clear, actionable error (matching getPathFromArtifacts), rather than aborting the whole mojo with an NPE that gives no hint of which dependency is the cause.