[KEYCLOAK-7569] support for authentication flow update

Added support for the PUT method of the authentication flow endpoint in
the admin API.

Now it's possible to run the 'update' method for authentication/flows in
kcadm.sh.

services/src/main/java/org/keycloak/services/resources/admin/AuthenticationManagementResource.java

@@ -246,6 +246,32 @@ public class AuthenticationManagementResource {
         return ModelToRepresentation.toRepresentation(realm, flow);
     }
 
+    /**
+     * Update an authentication flow
+     *
+     * @param flow Authentication flow representation
+     * @return
+     */
+    @Path("/flows/{id}")
+    @PUT
+    @NoCache
+    @Consumes(MediaType.APPLICATION_JSON)
+    public Response updateFlow(@PathParam("id") String id, AuthenticationFlowRepresentation flow) {
+        auth.realm().requireManageRealm();
+
+        AuthenticationFlowRepresentation existingFlow = getFlow(id);
+
+        if (flow.getAlias() == null || flow.getAlias().isEmpty()) {
+            return ErrorResponse.exists("Failed to update flow with empty alias name");
+        }
+
+        flow.setId(existingFlow.getId());
+        realm.updateAuthenticationFlow(RepresentationToModel.toModel(flow));
+        adminEvent.operation(OperationType.UPDATE).resourcePath(uriInfo).representation(flow).success();
+
+        return Response.accepted(flow).build();
+    }
+
     /**
      * Delete an authentication flow
      *