FieldType::mergeValue

public function mergeValue($baseValue, $appendValue): array
{
	$typeClass = $this->typeClass;
	$baseValue = (array) $baseValue;

	if ($this->isMultiple() && !CBPHelper::isEmptyValue($appendValue))
	{
		return $typeClass::mergeValue($this, $baseValue, $appendValue);
	}

	return $baseValue;
}