in src/main/java/org/apache/maven/resolver/internal/ant/types/Artifact.java [78:89]
public void setFile(final File file) {
checkAttributesAllowed();
this.file = file;
if (file != null && type == null) {
final String name = file.getName();
final int period = name.lastIndexOf('.');
if (period >= 0) {
type = name.substring(period + 1);
}
}
}