Added Changes on SDK Side to register its Implemented Interfaces (#508)

* added required changes from the sdk part
Signed-off-by: varuntumbe <[email protected]>

* SpotlessApply Done. Replaced Wildcard Imports.
Signed-off-by: varuntumbe <[email protected]>

* Add required javadoc

Signed-off-by: Daniel Widdis <[email protected]>

---------

Signed-off-by: Daniel Widdis <[email protected]>
Co-authored-by: Daniel Widdis <[email protected]>

src/main/java/org/opensearch/sdk/ExtensionsRunner.java

@@ -56,11 +56,15 @@
 
 import java.io.IOException;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collections;
+import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
+import java.util.Set;
 import java.util.concurrent.TimeoutException;
 import java.util.function.Consumer;
+import java.util.stream.Collectors;
 
 /**
  * The primary class to run an extension.
@@ -388,6 +392,33 @@ public void startTransportService(TransportService transportService) {
 
     }
 
+    /**
+     * Returns a list of interfaces implemented by the corresponding {@link Extension}.
+     *
+     * @return A list of strings matching the interface name.
+     */
+    public List<String> getExtensionImplementedInterfaces() {
+        Extension extension = getExtension();
+
+        Set<Class<?>> interfaceSet = new HashSet<>();
+        Class<?> extensionClass = extension.getClass();
+        do {
+            interfaceSet.addAll(Arrays.stream(extensionClass.getInterfaces()).collect(Collectors.toSet()));
+            extensionClass = extensionClass.getSuperclass();
+        } while (extensionClass != null);
+
+        List<String> interfacesOfOpenSearch = new ArrayList<String>();
+        // we are making an assumption here that all the other Interfaces will be in the same package ( or will be in subpackage ) in which
+        // ActionExtension Interface belongs.
+        String packageNameOfActionExtension = ActionExtension.class.getPackageName();
+        for (Class<?> anInterface : interfaceSet) {
+            if (anInterface.getPackageName().startsWith(packageNameOfActionExtension)) {
+                interfacesOfOpenSearch.add(anInterface.getSimpleName());
+            }
+        }
+        return interfacesOfOpenSearch;
+    }
+
     /**
      * Requests that OpenSearch register the REST Actions for this extension.
      *

src/main/java/org/opensearch/sdk/handlers/ExtensionsInitRequestHandler.java

@@ -50,7 +50,10 @@ public InitializeExtensionResponse handleExtensionInitRequest(InitializeExtensio
         extensionsRunner.setUniqueId(extensionInitRequest.getExtension().getId());
         // Successfully initialized. Send the response.
         try {
-            return new InitializeExtensionResponse(extensionsRunner.getSettings().get(NODE_NAME_SETTING));
+            return new InitializeExtensionResponse(
+                extensionsRunner.getSettings().get(NODE_NAME_SETTING),
+                extensionsRunner.getExtensionImplementedInterfaces()
+            );
         } finally {
             // After sending successful response to initialization, send the REST API and Settings
             extensionsRunner.setOpensearchNode(extensionsRunner.opensearchNode);

src/test/java/org/opensearch/sdk/TestExtensionsRunner.java

@@ -28,6 +28,7 @@
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashMap;
+import java.util.List;
 
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
@@ -235,4 +236,13 @@ public void testGettersAndSetters() throws IOException {
         assertEquals(ExtensionsRunnerForTest.NODE_HOST, settings.get(TransportSettings.BIND_HOST.getKey()));
         assertEquals(ExtensionsRunnerForTest.NODE_PORT, settings.get(TransportSettings.PORT.getKey()));
     }
+
+    @Test
+    public void testGetExtensionImplementedInterfaces() {
+        List<String> implementedInterfaces = extensionsRunner.getExtensionImplementedInterfaces();
+        assertTrue(!implementedInterfaces.isEmpty());
+        assertTrue(implementedInterfaces.contains("Extension"));
+        assertTrue(implementedInterfaces.contains("ActionExtension"));
+    }
+
 }