Make multiple fields nullable (nilable) in networking interface (#451)

* Make multiple fields nullable (nilable) in networking interface

* Update test fixtures

instance_config_interfaces.go

@@ -16,13 +16,13 @@ type InstanceConfigInterface struct {
 	Active      bool                   `json:"active"`
 	VPCID       *int                   `json:"vpc_id"`
 	SubnetID    *int                   `json:"subnet_id"`
-	IPv4        VPCIPv4                `json:"ipv4"`
+	IPv4        *VPCIPv4               `json:"ipv4"`
 	IPRanges    []string               `json:"ip_ranges"`
 }
 
 type VPCIPv4 struct {
-	VPC     string `json:"vpc,omitempty"`
-	NAT1To1 string `json:"nat_1_1,omitempty"`
+	VPC     string  `json:"vpc,omitempty"`
+	NAT1To1 *string `json:"nat_1_1,omitempty"`
 }
 
 type InstanceConfigInterfaceCreateOptions struct {
@@ -67,20 +67,14 @@ func (i InstanceConfigInterface) GetCreateOptions() InstanceConfigInterfaceCreat
 		opts.IPRanges = i.IPRanges
 	}
 
-	if i.Purpose == InterfacePurposeVPC &&
-		i.IPv4.NAT1To1 != "" && i.IPv4.VPC != "" {
+	if i.Purpose == InterfacePurposeVPC && i.IPv4 != nil {
 		opts.IPv4 = &VPCIPv4{
 			VPC:     i.IPv4.VPC,
 			NAT1To1: i.IPv4.NAT1To1,
 		}
 	}
 
-	// workaround for API issue
-	if i.IPAMAddress == "222" {
-		opts.IPAMAddress = ""
-	} else {
-		opts.IPAMAddress = i.IPAMAddress
-	}
+	opts.IPAMAddress = i.IPAMAddress
 
 	return opts
 }
@@ -90,7 +84,7 @@ func (i InstanceConfigInterface) GetUpdateOptions() InstanceConfigInterfaceUpdat
 		Primary: i.Primary,
 	}
 
-	if i.Purpose == InterfacePurposeVPC {
+	if i.Purpose == InterfacePurposeVPC && i.IPv4 != nil {
 		opts.IPv4 = &VPCIPv4{
 			VPC:     i.IPv4.VPC,
 			NAT1To1: i.IPv4.NAT1To1,

test/integration/instance_config_test.go

@@ -78,6 +78,7 @@ func setupInstanceWith3Interfaces(t *testing.T, fixturesYaml string) (
 	}
 
 	updateConfigOpts := config.GetUpdateOptions()
+	NAT1To1Any := "any"
 	updateConfigOpts.Interfaces = []InstanceConfigInterfaceCreateOptions{
 		{
 			Purpose: InterfacePurposePublic,
@@ -90,7 +91,7 @@ func setupInstanceWith3Interfaces(t *testing.T, fixturesYaml string) (
 			Purpose:  InterfacePurposeVPC,
 			SubnetID: &vpcSubnet.ID,
 			IPv4: &VPCIPv4{
-				NAT1To1: "any",
+				NAT1To1: &NAT1To1Any,
 			},
 		},
 	}
@@ -282,6 +283,9 @@ func TestInstance_ConfigInterfaces_Update(t *testing.T) {
 		{
 			Purpose:  InterfacePurposeVPC,
 			SubnetID: &vpcSubnet.ID,
+			IPv4: &VPCIPv4{
+				VPC: "192.168.0.87",
+			},
 		},
 	}
 
@@ -370,10 +374,10 @@ func TestInstance_ConfigInterface_Update(t *testing.T) {
 	if !(updatedIntfc.Primary == updateOpts.Primary) {
 		t.Errorf("updating interface %v didn't succeed", intfc.ID)
 	}
-
+	NAT1To1Any := "any"
 	updateOpts.IPv4 = &VPCIPv4{
 		VPC:     "192.168.0.10",
-		NAT1To1: "any",
+		NAT1To1: &NAT1To1Any,
 	}
 
 	updatedIntfc, err = client.UpdateInstanceConfigInterface(