HMS-1832 fix: prevent changing domain name

Detect if client is attempting to change the domain name.  Return an
error if so.

Also remove processing related to Title, Description and
AutoEnrollmentEnabled fields.  These fields do not appear in the
UpdateDomainAgentRequest payload type.

internal/handler/impl/domain_handler.go

@@ -318,6 +318,15 @@ func (a *application) UpdateDomainAgent(ctx echo.Context, domain_id uuid.UUID, p
 		return err
 	}
 
+	if data.DomainName != nil &&
+		currentData.DomainName != nil &&
+		*data.DomainName != *currentData.DomainName {
+		return internal_errors.NewHTTPErrorF(
+			http.StatusBadRequest,
+			"'domain_name' may not be changed",
+		)
+	}
+
 	if err = a.fillDomain(currentData, data); err != nil {
 		return err
 	}

internal/usecase/repository/domain_repository.go

@@ -8,7 +8,6 @@ import (
 
 	"github.com/google/uuid"
 	"github.com/labstack/echo/v4"
-	"github.com/openlyinc/pointy"
 	"github.com/podengo-project/idmsvc-backend/internal/api/public"
 	"github.com/podengo-project/idmsvc-backend/internal/domain/model"
 	internal_errors "github.com/podengo-project/idmsvc-backend/internal/errors"
@@ -144,30 +143,6 @@ func (r *domainRepository) UpdateAgent(
 		return err
 	}
 
-	if data.DomainName != nil {
-		currentDomain.DomainName = data.DomainName
-	} else {
-		currentDomain.DomainName = pointy.String("")
-	}
-
-	if data.Title != nil {
-		currentDomain.Title = data.Title
-	} else {
-		currentDomain.Title = pointy.String("")
-	}
-
-	if data.Description != nil {
-		currentDomain.Description = data.Description
-	} else {
-		currentDomain.Description = pointy.String("")
-	}
-
-	if data.AutoEnrollmentEnabled != nil {
-		currentDomain.AutoEnrollmentEnabled = data.AutoEnrollmentEnabled
-	} else {
-		currentDomain.AutoEnrollmentEnabled = pointy.Bool(false)
-	}
-
 	if err = db.Omit(clause.Associations).
 		Where("org_id = ? AND domain_uuid = ?", orgID, currentDomain.DomainUuid).
 		Updates(data).