use empty struct for UserAssignedIdentities map value; omitempty

builder/azure/common/template/template.go

@@ -100,14 +100,10 @@ type Properties struct {
 }
 
 // Template > Resource > Identity
+// The map values are simplified to struct{} since they are read-only and cannot be set
 type Identity struct {
-	Type                   *string                                 `json:"type,omitempty"`
-	UserAssignedIdentities map[string]*UserAssignedIdentitiesValue `json:"userAssignedIdentities"`
-}
-
-type UserAssignedIdentitiesValue struct {
-	PrincipalId *string `json:"principalId,omitempty"`
-	ClientId    *string `json:"clientId,omitempty"`
+	Type                   *string             `json:"type,omitempty"`
+	UserAssignedIdentities map[string]struct{} `json:"userAssignedIdentities,omitempty"`
 }
 
 type AccessPolicies struct {

builder/azure/common/template/template_builder.go

@@ -115,10 +115,10 @@ func (s *TemplateBuilder) SetIdentity(userAssignedManagedIdentities []string) er
 		s.setVariable("apiVersion", "2018-06-01") // Required for user assigned managed identity
 		id = &Identity{
 			Type:                   to.StringPtr("UserAssigned"),
-			UserAssignedIdentities: make(map[string]*UserAssignedIdentitiesValue),
+			UserAssignedIdentities: make(map[string]struct{}),
 		}
 		for _, uid := range userAssignedManagedIdentities {
-			id.UserAssignedIdentities[uid] = &UserAssignedIdentitiesValue{}
+			id.UserAssignedIdentities[uid] = struct{}{}
 		}
 	}