See also:
- How does Magento 2 prepare a backend config form field for rendering?
- What is the «backend_model» for a backend configuration’s form field?
- The methods
\Magento\Framework\App\Config\ValueInterface::getFieldsetDataValue()and\Magento\Framework\App\Config\Value::getFieldsetDataValue()are declared but never used - The method
\Magento\Framework\App\Config\ValueInterface::isValueChanged()should be removed from the interface because it is used only internally by a particular interface implementation:\Magento\Framework\App\Config\Value - The method
\Magento\Framework\App\Config\ValueInterface::getOldValue()should be removed from the interface because it is used only internally by a particular interface implementation:\Magento\Framework\App\Config\Value - A backend model should always be a
\Magento\Framework\Model\AbstractModel