[Backport 2.x] Add seder to TransportPPLQueryResponse

plugin/src/main/java/org/opensearch/sql/plugin/transport/TransportPPLQueryResponse.java

@@ -5,10 +5,15 @@
 
 package org.opensearch.sql.plugin.transport;
 
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
 import java.io.IOException;
+import java.io.UncheckedIOException;
 import lombok.Getter;
 import lombok.RequiredArgsConstructor;
 import org.opensearch.core.action.ActionResponse;
+import org.opensearch.core.common.io.stream.InputStreamStreamInput;
+import org.opensearch.core.common.io.stream.OutputStreamStreamOutput;
 import org.opensearch.core.common.io.stream.StreamInput;
 import org.opensearch.core.common.io.stream.StreamOutput;
 
@@ -25,4 +30,22 @@ public TransportPPLQueryResponse(StreamInput in) throws IOException {
   public void writeTo(StreamOutput out) throws IOException {
     out.writeString(result);
   }
+
+  public static TransportPPLQueryResponse fromActionResponse(ActionResponse actionResponse) {
+    if (actionResponse instanceof TransportPPLQueryResponse) {
+      return (TransportPPLQueryResponse) actionResponse;
+    }
+
+    try (ByteArrayOutputStream baos = new ByteArrayOutputStream();
+        OutputStreamStreamOutput osso = new OutputStreamStreamOutput(baos)) {
+      actionResponse.writeTo(osso);
+      try (StreamInput input =
+          new InputStreamStreamInput(new ByteArrayInputStream(baos.toByteArray()))) {
+        return new TransportPPLQueryResponse(input);
+      }
+    } catch (IOException e) {
+      throw new UncheckedIOException(
+          "failed to parse ActionResponse into TransportPPLQueryResponse", e);
+    }
+  }
 }

plugin/src/test/java/org/opensearch/sql/plugin/transport/TransportPPLQueryResponseTest.java

@@ -0,0 +1,82 @@
+/*
+ * Copyright OpenSearch Contributors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package org.opensearch.sql.plugin.transport;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+
+import java.io.IOException;
+import java.lang.reflect.InvocationTargetException;
+import java.net.URI;
+import java.net.URISyntaxException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.ExpectedException;
+import org.opensearch.core.action.ActionResponse;
+
+public class TransportPPLQueryResponseTest {
+
+  @Rule public ExpectedException exceptionRule = ExpectedException.none();
+
+  @Test
+  public void testFromActionResponseSameClassloader() {
+    TransportPPLQueryResponse response1 = new TransportPPLQueryResponse("mock result");
+    TransportPPLQueryResponse response2 = TransportPPLQueryResponse.fromActionResponse(response1);
+    assertEquals(response1.getResult(), response2.getResult());
+  }
+
+  @Test
+  public void testFromActionResponseDifferentClassLoader()
+      throws ClassNotFoundException,
+          InstantiationException,
+          IllegalAccessException,
+          NoSuchMethodException,
+          InvocationTargetException,
+          URISyntaxException {
+    ClassLoader loader = TransportPPLQueryResponseTest.class.getClassLoader();
+    URI resourceURI =
+        loader
+            .getResource("org/opensearch/sql/plugin/transport/TransportPPLQueryResponse.class")
+            .toURI();
+    Path classFilePath = Paths.get(resourceURI);
+    CustomClassLoader classLoader1 = new CustomClassLoader(classFilePath);
+    CustomClassLoader classLoader2 = new CustomClassLoader(classFilePath);
+
+    Class<?> class1 =
+        classLoader1.findClass("org.opensearch.sql.plugin.transport.TransportPPLQueryResponse");
+    Class<?> class2 =
+        classLoader2.findClass("org.opensearch.sql.plugin.transport.TransportPPLQueryResponse");
+
+    assertFalse(class1.isAssignableFrom(class2));
+    String result = "mock result";
+    TransportPPLQueryResponse response2 =
+        TransportPPLQueryResponse.fromActionResponse(
+            (ActionResponse) class1.getDeclaredConstructor(String.class).newInstance(result));
+    assertEquals(result, response2.getResult());
+  }
+}
+
+class CustomClassLoader extends ClassLoader {
+
+  private final Path classFilePath;
+
+  public CustomClassLoader(Path classFilePath) {
+    this.classFilePath = classFilePath;
+  }
+
+  @Override
+  protected Class<?> findClass(String name) throws ClassNotFoundException {
+    try {
+      byte[] classBytes = Files.readAllBytes(classFilePath);
+      return defineClass(name, classBytes, 0, classBytes.length);
+    } catch (IOException e) {
+      throw new ClassNotFoundException("Failed to load class: " + name, e);
+    }
+  }
+}