fix subnetwork SecondaryIpRanges update issue

pkg/clients/subnetwork/subnetwork.go

@@ -124,6 +124,9 @@ func IsUpToDate(name string, in *v1beta1.SubnetworkParameters, observed *compute
 	if !ok {
 		return true, false, errors.New(errCheckUpToDate)
 	}
+	// empty the SecondaryIpRanges to ensure that SecondaryRanges will be deleted
+	// when the user removes them from the CR.
+	desired.SecondaryIpRanges = make([]*compute.SubnetworkSecondaryRange, 0)
 	GenerateSubnetwork(name, *in, desired)
 	if !cmp.Equal(desired.PrivateIpGoogleAccess, observed.PrivateIpGoogleAccess) {
 		return false, true, nil

pkg/clients/subnetwork/subnetwork_test.go

@@ -72,6 +72,10 @@ func params(m ...func(*v1beta1.SubnetworkParameters)) *v1beta1.SubnetworkParamet
 	return o
 }
 
+func removeSecondaryRanges(s *v1beta1.SubnetworkParameters) {
+	s.SecondaryIPRanges = nil
+}
+
 func subnetwork(m ...func(*compute.Subnetwork)) *compute.Subnetwork {
 	o := &compute.Subnetwork{
 		Description:           testDescription,
@@ -292,6 +296,17 @@ func TestIsUpToDate(t *testing.T) {
 			},
 			want: want{upToDate: false, privAcc: true},
 		},
+		"NotUpToDateSecondaryRanges": {
+			args: args{
+				name:    testName,
+				in:      params(removeSecondaryRanges),
+				current: subnetwork(),
+			},
+			want: want{
+				upToDate: false,
+				privAcc:  false,
+			},
+		},
 	}
 
 	for name, tc := range cases {