The real package, as opposed to the package we are documenting it with, Package.name
Source
String get packageName {
if (_packageName == null) {
String sourcePath = _libraryElement.source.fullName;
File file = new File(sourcePath);
if (file.existsSync()) {
_packageName = _getPackageName(file.parent);
if (_packageName == null) _packageName = '';
} else {
_packageName = '';
}
}
return _packageName;
}