[SPARK-29158][SQL] Expose SerializableConfiguration for DataSource V2 developers

core/src/main/java/org/apache/spark/util/SerializableConfigurationSuite.java

@@ -0,0 +1,28 @@
+/*
+ * 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.spark.util;
+
+/**
+ * This test ensures that the API we've exposed for SerializableConfiguration is usable
+ * from Java. It does not test any of the serialization it's self.
+ */
+class SerializableConfigurationSuite {
+  public SerializableConfiguration compileTest() {
+    SerializableConfiguration scs = new SerializableConfiguration(null);
+    return scs;
+  }
+}

core/src/main/scala/org/apache/spark/util/SerializableConfiguration.scala

@@ -20,7 +20,13 @@ import java.io.{ObjectInputStream, ObjectOutputStream}
 
 import org.apache.hadoop.conf.Configuration
 
-private[spark]
+import org.apache.spark.annotation.{DeveloperApi, Unstable}
+
+/**
+ * Helper wrapper to serialize a Hadoop configuration. Intended for use when implementing
+ * DataSourceV2 readers & writers which depend on the Hadoop configuration from the driver node.
+ */
+@DeveloperApi @Unstable
 class SerializableConfiguration(@transient var value: Configuration) extends Serializable {
   private def writeObject(out: ObjectOutputStream): Unit = Utils.tryOrIOException {
     out.defaultWriteObject()