in src/main/java/org/apache/maven/plugins/jarsigner/AbstractJarsignerMojo.java [405:420]
private Optional<File> getFileFromArtifact(final Artifact artifact) {
if (artifact == null) {
throw new NullPointerException("artifact");
}
if (isZipFile(artifact)) {
return Optional.of(artifact.getFile());
}
if (this.verbose) {
getLog().info(getMessage("unsupported", artifact));
} else if (getLog().isDebugEnabled()) {
getLog().debug(getMessage("unsupported", artifact));
}
return Optional.empty();
}