fix: correct ActiveClusters deepcopy method (#7394)

<!-- Describe what has changed in this PR -->
**What changed?**
small bugfix for a deepcopy method which wasn't working as advertised

<!-- Tell your future self why have you made these changes -->
**Why?**


<!-- How have you verified this change? Tested locally? Added a unit
test? Checked in staging env? -->
**How did you test it?**


<!-- Assuming the worst case, what can be broken when deploying this
change to production? -->
**Potential risks**

<!-- Is it notable for release? e.g. schema updates, configuration or
data migration required? If so, please mention it, and also update
CHANGELOG.md -->
**Release notes**

<!-- Is there any documentation updates should be made for config,
https://cadenceworkflow.io/docs/operation-guide/setup/ ? If so, please
open an PR in https://github.com/cadence-workflow/cadence-docs -->
**Documentation Changes**

Signed-off-by: David Porter <[email protected]>

Author: davidporter-id-au

common/types/shared.go

@@ -2731,7 +2731,14 @@ func (v *ActiveClusters) DeepCopy() *ActiveClusters {
 	if v.AttributeScopes != nil {
 		result.AttributeScopes = make(map[string]ClusterAttributeScope, len(v.AttributeScopes))
 		for scopeType, scope := range v.AttributeScopes {
-			result.AttributeScopes[scopeType] = scope
+			copiedScope := ClusterAttributeScope{}
+			if scope.ClusterAttributes != nil {
+				copiedScope.ClusterAttributes = make(map[string]ActiveClusterInfo, len(scope.ClusterAttributes))
+				for attrName, attrInfo := range scope.ClusterAttributes {
+					copiedScope.ClusterAttributes[attrName] = attrInfo
+				}
+			}
+			result.AttributeScopes[scopeType] = copiedScope
 		}
 	}
 	return result

common/types/shared_test.go

@@ -130,6 +130,41 @@ func TestActiveClustersConfigDeepCopy(t *testing.T) {
 	}
 }
 
+// Todo (david.porter) delete this test and codegen this
+func TestActiveClustersDeepCopyMutationIsolation(t *testing.T) {
+
+	t.Run("modifying nested ClusterAttributes map in original should not affect copy", func(t *testing.T) {
+		original := &ActiveClusters{
+			AttributeScopes: map[string]ClusterAttributeScope{
+				"region": {
+					ClusterAttributes: map[string]ActiveClusterInfo{
+						"us-east-1": {
+							ActiveClusterName: "cluster1",
+							FailoverVersion:   100,
+						},
+					},
+				},
+			},
+		}
+
+		copied := original.DeepCopy()
+
+		assert.Equal(t, original, copied)
+
+		scope := original.AttributeScopes["region"]
+		scope.ClusterAttributes["us-west-1"] = ActiveClusterInfo{
+			ActiveClusterName: "cluster2",
+			FailoverVersion:   200,
+		}
+		original.AttributeScopes["region"] = scope
+
+		assert.Len(t, original.AttributeScopes["region"].ClusterAttributes, 2)
+		assert.Len(t, copied.AttributeScopes["region"].ClusterAttributes, 1)
+		assert.Contains(t, original.AttributeScopes["region"].ClusterAttributes, "us-west-1")
+		assert.NotContains(t, copied.AttributeScopes["region"].ClusterAttributes, "us-west-1")
+	})
+}
+
 func TestIsActiveActiveDomain(t *testing.T) {
 	tests := []struct {
 		name           string