# File lib/fog/aws/requests/compute/create_route.rb, line 42
        def create_route(route_table_id, destination_cidr_block, internet_gateway_id=nil, instance_id=nil, network_interface_id=nil)
          instance_owner_id = nil
          route_table = self.data[:route_tables].find { |routetable| routetable["routeTableId"].eql? route_table_id }
          if !route_table.nil? && destination_cidr_block
            if !internet_gateway_id.nil? || !instance_id.nil? || !network_interface_id.nil?
              if !internet_gateway_id.nil? && self.internet_gateways.all('internet-gateway-id'=>internet_gateway_id).first.nil?
                raise Fog::Compute::AWS::NotFound.new("The gateway ID '#{internet_gateway_id}' does not exist")
              elsif !instance_id.nil? && self.servers.all('instance-id'=>instance_id).first.nil?
                raise Fog::Compute::AWS::NotFound.new("The instance ID '#{instance_id}' does not exist")
              elsif !network_interface_id.nil? && self.network_interfaces.all('networkInterfaceId'=>network_interface_id).first.nil?
                raise Fog::Compute::AWS::NotFound.new("The networkInterface ID '#{network_interface_id}' does not exist")
              elsif !route_table['routeSet'].find { |route| route['destinationCidrBlock'].eql? destination_cidr_block }.nil?
                raise Fog::Compute::AWS::Error, "RouteAlreadyExists => The route identified by #{destination_cidr_block} already exists."
              else
                response = Excon::Response.new
                route_table['routeSet'].push({
                  "destinationCidrBlock" => destination_cidr_block,
                  "gatewayId" => internet_gateway_id,
                  "instanceId"=>instance_id,
                  "instanceOwnerId"=>instance_owner_id,
                  "networkInterfaceId"=>network_interface_id,
                  "state" => "pending",
                  "origin" => "CreateRoute"
                })
                response.status = 200
                response.body = {
                  'requestId'=> Fog::AWS::Mock.request_id,
                  'return' => true
                }
                response
              end
            else
              message = 'MissingParameter => '
              message << 'The request must contain either a gateway id, a network interface id, or an instance id'
              raise Fog::Compute::AWS::Error.new(message)
            end
          elsif route_table.nil?
            raise Fog::Compute::AWS::NotFound.new("The routeTable ID '#{route_table_id}' does not exist")
          elsif destination_cidr_block.empty?
            raise Fog::Compute::AWS::InvalidParameterValue.new("Value () for parameter destinationCidrBlock is invalid. This is not a valid CIDR block.")
          end
        end