chore: use k8s equality package to compare structs instead of reflect (aws-controllers-k8s#653)

Description of changes:
Replace `reflect.DeepEqual` with `equality.Semantic.DeepEqual` from
`k8s.io/apimachinery/pkg/api/equality` for comparing Kubernetes objects.

Why this change:

1. Nil vs Empty equivalence: Semantic equality treats nil slices/maps
   as equal to empty slices/maps. This prevents false negatives when
   comparing API objects where nil and empty are semantically identical.

2. Proper time.Time comparison: Uses time.Time.Equal() internally,
   which correctly compares timestamps across different timezone
   representations and monotonic clock readings.

Example of the problem:
  - `reflect.DeepEqual([]string{}, nil)` => false
  - `equality.Semantic.DeepEqual([]string{}, nil)` => true

Both serialize to the same JSON/YAML, so they should be considered equal
when comparing Kubernetes resources.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

Author: michaelhtm

pkg/generate/code/compare.go

@@ -140,11 +140,11 @@ func CompareResource(
 			cfg.PrefixConfig.SpecField+"."+specField.Names.Camel, ".",
 		)
 
-		// Use reflect.DeepEqual for comparing Reference fields because
+		// Use equality.Semantic.Equalities.DeepEqual for comparing Reference fields because
 		// some of reference fields are list of pointer to structs and
 		// DeepEqual is easy way to compare them
 		if specField.IsReference() {
-			out += fmt.Sprintf("%sif !reflect.DeepEqual(%s, %s) {\n",
+			out += fmt.Sprintf("%sif !equality.Semantic.Equalities.DeepEqual(%s, %s) {\n",
 				indent, firstResAdaptedVarName, secondResAdaptedVarName)
 			out += fmt.Sprintf("%s\t%s.Add(\"%s\", %s, %s)\n", indent,
 				deltaVarName, fieldPath, firstResAdaptedVarName,
@@ -425,7 +425,7 @@ func compareMap(
 		// building up the fieldPath appropriately and calling into a
 		// struct-specific comparator function...
 		out += fmt.Sprintf(
-			"%sif !reflect.DeepEqual(%s, %s) {\n",
+			"%sif !equality.Semantic.Equalities.DeepEqual(%s, %s) {\n",
 			indent, firstResVarName, secondResVarName,
 		)
 	}
@@ -497,7 +497,7 @@ func compareSlice(
 		// comparator function...the tricky part of this is figuring out how to
 		// sort the slice of structs...
 		out += fmt.Sprintf(
-			"%sif !reflect.DeepEqual(%s, %s) {\n",
+			"%sif !equality.Semantic.Equalities.DeepEqual(%s, %s) {\n",
 			indent, firstResVarName, secondResVarName,
 		)
 	default:

pkg/generate/code/compare_test.go

@@ -97,7 +97,7 @@ func TestCompareResource_S3_Bucket(t *testing.T) {
 			if len(a.ko.Spec.Logging.LoggingEnabled.TargetGrants) != len(b.ko.Spec.Logging.LoggingEnabled.TargetGrants) {
 				delta.Add("Spec.Logging.LoggingEnabled.TargetGrants", a.ko.Spec.Logging.LoggingEnabled.TargetGrants, b.ko.Spec.Logging.LoggingEnabled.TargetGrants)
 			} else if len(a.ko.Spec.Logging.LoggingEnabled.TargetGrants) > 0 {
-				if !reflect.DeepEqual(a.ko.Spec.Logging.LoggingEnabled.TargetGrants, b.ko.Spec.Logging.LoggingEnabled.TargetGrants) {
+				if !equality.Semantic.Equalities.DeepEqual(a.ko.Spec.Logging.LoggingEnabled.TargetGrants, b.ko.Spec.Logging.LoggingEnabled.TargetGrants) {
 					delta.Add("Spec.Logging.LoggingEnabled.TargetGrants", a.ko.Spec.Logging.LoggingEnabled.TargetGrants, b.ko.Spec.Logging.LoggingEnabled.TargetGrants)
 				}
 			}
@@ -274,7 +274,7 @@ func TestCompareResource_Lambda_Function(t *testing.T) {
 	if len(a.ko.Spec.FileSystemConfigs) != len(b.ko.Spec.FileSystemConfigs) {
 		delta.Add("Spec.FileSystemConfigs", a.ko.Spec.FileSystemConfigs, b.ko.Spec.FileSystemConfigs)
 	} else if len(a.ko.Spec.FileSystemConfigs) > 0 {
-		if !reflect.DeepEqual(a.ko.Spec.FileSystemConfigs, b.ko.Spec.FileSystemConfigs) {
+		if !equality.Semantic.Equalities.DeepEqual(a.ko.Spec.FileSystemConfigs, b.ko.Spec.FileSystemConfigs) {
 			delta.Add("Spec.FileSystemConfigs", a.ko.Spec.FileSystemConfigs, b.ko.Spec.FileSystemConfigs)
 		}
 	}
@@ -485,7 +485,7 @@ func TestCompareResource_APIGatewayv2_Route(t *testing.T) {
 	if len(a.ko.Spec.RequestParameters) != len(b.ko.Spec.RequestParameters) {
 		delta.Add("Spec.RequestParameters", a.ko.Spec.RequestParameters, b.ko.Spec.RequestParameters)
 	} else if len(a.ko.Spec.RequestParameters) > 0 {
-		if !reflect.DeepEqual(a.ko.Spec.RequestParameters, b.ko.Spec.RequestParameters) {
+		if !equality.Semantic.Equalities.DeepEqual(a.ko.Spec.RequestParameters, b.ko.Spec.RequestParameters) {
 			delta.Add("Spec.RequestParameters", a.ko.Spec.RequestParameters, b.ko.Spec.RequestParameters)
 		}
 	}

templates/pkg/resource/delta.go.tpl

@@ -4,16 +4,15 @@ package {{ .CRD.Names.Snake }}
 
 import (
 	"bytes"
-	"reflect"
 
+	"k8s.io/apimachinery/pkg/api/equality"
 	ackcompare "github.com/aws-controllers-k8s/runtime/pkg/compare"
 	acktags "github.com/aws-controllers-k8s/runtime/pkg/tags"
 )
 
 // Hack to avoid import errors during build...
 var (
 	_ = &bytes.Buffer{}
-	_ = &reflect.Method{}
 	_ = &acktags.Tags{}
 )