Add license header to event_error.rs

Signed-off-by: Nicola Bonelli <nicola.bonelli@huawei-partners.com>

Author: awgn

orion-lib/src/event_error.rs

@@ -1,3 +1,20 @@
+// Copyright 2025 The kmesh Authors
+//
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+//
+
 use http::Response;
 use orion_format::types::ResponseFlags as FmtResponseFlags;
 use std::error::Error as ErrorTrait;