in src/main/java/org/apache/maven/plugins/artifact/buildinfo/CompareMojo.java [139:149]
private void checkAgainstReference(Map<Artifact, String> artifacts, boolean mono) throws MojoExecutionException {
MavenProject root = mono ? project : session.getTopLevelProject();
File referenceDir = new File(root.getBuild().getDirectory(), "reference");
referenceDir.mkdirs();
// download or create reference buildinfo
File referenceBuildinfo = downloadOrCreateReferenceBuildinfo(mono, artifacts, referenceDir);
// compare outputs from reference buildinfo vs actual
compareWithReference(artifacts, referenceBuildinfo);
}