Terraform cdktf routetable - route [{ }] ignore some attribute

Terraform
1

const route1table = new RouteTable(this, “route1table”, {

  vpcId: vpcs.id,

  route: [{

    cidrBlock: route_block.stringValue,

    gatewayId: gateway.id,

    egressOnlyGatewayId: undefined ,

    carrierGatewayId: undefined ,

    instanceId: undefined,

    natGatewayId: undefined ,

    networkInterfaceId: undefined ,

    ipv6CidrBlock: undefined ,

    vpcEndpointId: undefined , 

    vpcPeeringConnectionId: undefined ,

  }],

  count: 3

})

error │ Inappropriate value for attribute “route”: element 0: attributes

how to ignore those attributes in undefined and just use only defined attribute in route table for stack