public function getBaseTypeClass()
    {
        // If we have a base type which is different than the current class then extend that.
        // It is actually possible to have different classes with the same name as PHP SoapClient has a poor
        // understanding of namespaces. Two types with the same name but in different namespaces will have the same
        // identifier.
        if ($this->baseType !== null && $this->baseType !== $this) {
            return $this->baseType->getPhpIdentifier();
        }

        return null;
    }