avoid using package private Akka S3Exception class

common/scala/src/main/scala/org/apache/openwhisk/core/database/s3/S3AttachmentStore.scala

@@ -26,7 +26,7 @@ import akka.http.scaladsl.model.{ContentType, HttpRequest, HttpResponse, Uri}
 import akka.http.scaladsl.unmarshalling.Unmarshal
 import akka.stream.alpakka.s3.headers.CannedAcl
 import akka.stream.alpakka.s3.scaladsl.S3
-import akka.stream.alpakka.s3.{S3Attributes, S3Exception, S3Headers, S3Settings}
+import akka.stream.alpakka.s3.{S3Attributes, S3Headers, S3Settings}
 import akka.stream.scaladsl.{Sink, Source}
 import akka.util.ByteString
 import com.typesafe.config.Config

common/scala/src/main/scala/org/apache/openwhisk/core/database/s3/S3Exception.scala

@@ -0,0 +1,20 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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.
+ */
+
+package org.apache.openwhisk.core.database.s3
+
+class S3Exception(msg: String) extends Exception(msg)