Pimcore\Model\Object\ClassDefinition::extractDataDefinitions PHP Method

    public function extractDataDefinitions($def)
    {
        if ($def instanceof Object\ClassDefinition\Layout) {
            if ($def->hasChilds()) {
                foreach ($def->getChilds() as $child) {
                    $this->extractDataDefinitions($child);
                }
            }
        }
        if ($def instanceof Object\ClassDefinition\Data) {
            $existing = $this->getFieldDefinition($def->getName());
            if ($existing && method_exists($existing, "addReferencedField")) {
                // this is especially for localized fields which get aggregated here into one field definition
                // in the case that there are more than one localized fields in the class definition
                // see also pimcore.object.edit.addToDataFields();
                $existing->addReferencedField($def);
            } else {
                $this->addFieldDefinition($def->getName(), $def);
            }
        }
    }