Node::prepareFieldDefinition

static function prepareFieldDefinition(array $field)
{
	$field = array_change_key_case($field, CASE_LOWER);
	$field['id'] = static::prepareStringValue($field, 'id');
	$field['type'] = static::prepareStringValue($field, 'type');
	$field['name'] = static::prepareStringValue($field, 'name');
	if (empty($field['id']) || empty($field['type']) || empty($field['name']))
	{
		return null;
	}

	/** @var Node $className */
	$className = NodeType::getClassName($field['type']);
	if (!class_exists($className))
	{
		return null;
	}
	return $className::validateFieldDefinition($field);
}