src/Entity/AbstractEntity.php
public function __isset($property)
    {
        trigger_error(
            sprintf(
                'Using isset() with entity properties is deprecated. Use %s::notEmpty("%s") instead.',
                get_class($this),
                $property
            ),
            E_USER_DEPRECATED
        );
        return $this->notEmpty($property);
    }
public function __isset($property)
    {
        trigger_error(
            sprintf(
                'Using isset() with entity properties is deprecated. Use %s::notEmpty("%s") instead.',
                get_class($this),
                $property
            ),
            E_USER_DEPRECATED
        );
        return $this->notEmpty($property);
    }
Checks if a property exists and has a non-empty value.

If the property is an array, the check will return, if this
array has items or not.

@deprecated since 0.25 Use {@link notEmpty()}
@param string $property
@return boolean