move MergeMaps func into pkg/restore where it's used

Signed-off-by: Steve Kriss <krisss@vmware.com>

pkg/restore/merge_service_account.go

@@ -24,8 +24,6 @@ import (
 	"k8s.io/apimachinery/pkg/api/equality"
 	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
 	"k8s.io/apimachinery/pkg/runtime"
-
-	"github.com/heptio/velero/pkg/util/collections"
 )
 
 // mergeServiceAccount takes a backed up serviceaccount and merges attributes into the current in-cluster service account.
@@ -46,9 +44,9 @@ func mergeServiceAccounts(fromCluster, fromBackup *unstructured.Unstructured) (*
 
 	desired.ImagePullSecrets = mergeLocalObjectReferenceSlices(desired.ImagePullSecrets, backupSA.ImagePullSecrets)
 
-	desired.Labels = collections.MergeMaps(desired.Labels, backupSA.Labels)
+	desired.Labels = mergeMaps(desired.Labels, backupSA.Labels)
 
-	desired.Annotations = collections.MergeMaps(desired.Annotations, backupSA.Annotations)
+	desired.Annotations = mergeMaps(desired.Annotations, backupSA.Annotations)
 
 	desiredUnstructured, err := runtime.DefaultUnstructuredConverter.ToUnstructured(desired)
 	if err != nil {
@@ -95,6 +93,24 @@ func mergeLocalObjectReferenceSlices(first, second []corev1api.LocalObjectRefere
 	return first
 }
 
+// mergeMaps takes two map[string]string and merges missing keys from the second into the first.
+// If a key already exists, its value is not overwritten.
+func mergeMaps(first, second map[string]string) map[string]string {
+	// If the first map passed in is empty, just use all of the second map's data
+	if first == nil {
+		first = map[string]string{}
+	}
+
+	for k, v := range second {
+		_, ok := first[k]
+		if !ok {
+			first[k] = v
+		}
+	}
+
+	return first
+}
+
 // generatePatch will calculate a JSON merge patch for an object's desired state.
 // If the passed in objects are already equal, nil is returned.
 func generatePatch(fromCluster, desired *unstructured.Unstructured) ([]byte, error) {

pkg/restore/merge_service_account_test.go

@@ -315,6 +315,60 @@ func stripWhitespace(s string) string {
 	}, s)
 }
 
+func TestMergeMaps(t *testing.T) {
+	var testCases = []struct {
+		name        string
+		source      map[string]string
+		destination map[string]string
+		expected    map[string]string
+	}{
+		{
+			name:        "nil destination should result in source being copied",
+			destination: nil,
+			source: map[string]string{
+				"k1": "v1",
+			},
+			expected: map[string]string{
+				"k1": "v1",
+			},
+		},
+		{
+			name: "keys missing from destination should be copied from source",
+			destination: map[string]string{
+				"k2": "v2",
+			},
+			source: map[string]string{
+				"k1": "v1",
+			},
+			expected: map[string]string{
+				"k1": "v1",
+				"k2": "v2",
+			},
+		},
+		{
+			name: "matching key should not have value copied from source",
+			destination: map[string]string{
+				"k1": "v1",
+			},
+			source: map[string]string{
+				"k1": "v2",
+			},
+			expected: map[string]string{
+				"k1": "v1",
+			},
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+
+			result := mergeMaps(tc.destination, tc.source)
+
+			assert.Equal(t, tc.expected, result)
+		})
+	}
+}
+
 func TestGeneratePatch(t *testing.T) {
 	tests := []struct {
 		name           string