fix: LoadBalancerUpdateServiceOpts not converted correctly (#394)

In the conversion from LoadBalancerUpdateServiceOpts to
schema.LoadBalancerActionUpdateServiceRequest, there are conversions
from slices to slice pointers. Slice pointers exist in schemas to
differentiate between absent and empty.

Goverter converts nil slices to &nil. This leads to the field being
marshaled to `null` in JSON (even with the `omitempty` flag) instead of
being not present (See hetznercloud/cli#702)

This PR fixes this issue by adding manual conversion methods and adds
tests to account for this behavior.

---------

Co-authored-by: pauhull <[email protected]>

Author: phm07

hcloud/schema_gen.go

@@ -78,6 +78,8 @@ You can find a documentation of goverter here: https://goverter.jmattheis.de/
 // goverter:extend schemaFromLoadBalancerCreateOptsTargetServer
 // goverter:extend schemaFromLoadBalancerCreateOptsTargetIP
 // goverter:extend stringMapToStringMapPtr
+// goverter:extend int64SlicePtrFromCertificatePtrSlice
+// goverter:extend stringSlicePtrFromStringSlice
 type converter interface {
 
 	// goverter:map Error.Code ErrorCode
@@ -926,3 +928,22 @@ func mapZeroFloat32ToNil(f float32) *float32 {
 func isDeprecationNotNil(d *DeprecationInfo) bool {
 	return d != nil
 }
+
+// int64SlicePtrFromCertificatePtrSlice is needed so that a nil slice is mapped to nil instead of &nil.
+func int64SlicePtrFromCertificatePtrSlice(s []*Certificate) *[]int64 {
+	if s == nil {
+		return nil
+	}
+	var ids = make([]int64, len(s))
+	for i, cert := range s {
+		ids[i] = cert.ID
+	}
+	return &ids
+}
+
+func stringSlicePtrFromStringSlice(s []string) *[]string {
+	if s == nil {
+		return nil
+	}
+	return &s
+}

hcloud/schema_test.go

@@ -1797,8 +1797,18 @@ func TestLoadBalancerUpdateServiceOptsToSchema(t *testing.T) {
 		Request schema.LoadBalancerActionUpdateServiceRequest
 	}{
 		"empty": {
-			Opts:    LoadBalancerUpdateServiceOpts{},
-			Request: schema.LoadBalancerActionUpdateServiceRequest{},
+			Opts: LoadBalancerUpdateServiceOpts{
+				HTTP: &LoadBalancerUpdateServiceOptsHTTP{},
+				HealthCheck: &LoadBalancerUpdateServiceOptsHealthCheck{
+					HTTP: &LoadBalancerUpdateServiceOptsHealthCheckHTTP{},
+				},
+			},
+			Request: schema.LoadBalancerActionUpdateServiceRequest{
+				HTTP: &schema.LoadBalancerActionUpdateServiceRequestHTTP{},
+				HealthCheck: &schema.LoadBalancerActionUpdateServiceRequestHealthCheck{
+					HTTP: &schema.LoadBalancerActionUpdateServiceRequestHealthCheckHTTP{},
+				},
+			},
 		},
 		"all set": {
 			Opts: LoadBalancerUpdateServiceOpts{