in maven-3.0.x/src/main/java/org/sonatype/aether/util/artifact/DefaultArtifact.java [241:258]
public DefaultArtifact( String groupId, String artifactId, String classifier, String extension, String version,
Map<String, String> properties, File file )
{
this.groupId = emptify( groupId );
this.artifactId = emptify( artifactId );
this.classifier = emptify( classifier );
this.extension = emptify( extension );
this.version = emptify( version );
this.file = file;
if ( properties != null && !properties.isEmpty() )
{
this.properties = new HashMap<String, String>( properties );
}
else
{
this.properties = Collections.emptyMap();
}
}