fix(grpc): allow omitted push config ids

client/transport/grpc/pom.xml

@@ -51,6 +51,11 @@
             <artifactId>junit-jupiter-api</artifactId>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>io.grpc</groupId>
+            <artifactId>grpc-inprocess</artifactId>
+            <scope>test</scope>
+        </dependency>
 
         <dependency>
             <groupId>org.mock-server</groupId>
@@ -59,4 +64,4 @@
         </dependency>
     </dependencies>
 
-</project>
+</project>

client/transport/grpc/src/main/java/org/a2aproject/sdk/client/transport/grpc/GrpcTransport.java

@@ -256,12 +256,12 @@ public TaskPushNotificationConfig getTaskPushNotificationConfiguration(GetTaskPu
             @Nullable ClientCallContext context) throws A2AClientException {
         checkNotNullParam("request", request);
         checkNotNullParam("taskId", request.taskId());
-        checkNotNullParam("id", request.id());
+        String configId = request.id();
 
         org.a2aproject.sdk.grpc.GetTaskPushNotificationConfigRequest grpcRequest = org.a2aproject.sdk.grpc.GetTaskPushNotificationConfigRequest.newBuilder()
                 .setTaskId(request.taskId())
                 .setTenant(resolveTenant(request.tenant()))
-                .setId(request.id())
+                .setId(configId == null ? "" : configId)
                 .build();
         PayloadAndHeaders payloadAndHeaders = applyInterceptors(GET_TASK_PUSH_NOTIFICATION_CONFIG_METHOD, grpcRequest, agentCard, context);
 

client/transport/grpc/src/test/java/org/a2aproject/sdk/client/transport/grpc/GrpcTransportTest.java

@@ -0,0 +1,119 @@
+package org.a2aproject.sdk.client.transport.grpc;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+
+import java.util.List;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicReference;
+
+import io.grpc.ManagedChannel;
+import io.grpc.Server;
+import io.grpc.inprocess.InProcessChannelBuilder;
+import io.grpc.inprocess.InProcessServerBuilder;
+import io.grpc.stub.StreamObserver;
+import org.a2aproject.sdk.grpc.A2AServiceGrpc;
+import org.a2aproject.sdk.grpc.GetTaskPushNotificationConfigRequest;
+import org.a2aproject.sdk.spec.AgentCapabilities;
+import org.a2aproject.sdk.spec.AgentCard;
+import org.a2aproject.sdk.spec.AgentInterface;
+import org.a2aproject.sdk.spec.GetTaskPushNotificationConfigParams;
+import org.a2aproject.sdk.spec.TaskPushNotificationConfig;
+import org.jspecify.annotations.Nullable;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.Timeout;
+
+@Timeout(5)
+class GrpcTransportTest {
+
+    private static final String TASK_ID = "task-1";
+    private static final String CALLBACK_URL = "https://example.com/callback";
+    private static final AgentCard CARD = AgentCard.builder()
+            .name("Test Agent")
+            .description("Agent for gRPC transport tests")
+            .version("1.0.0")
+            .supportedInterfaces(List.of(new AgentInterface("GRPC", "http://localhost")))
+            .capabilities(AgentCapabilities.builder().pushNotifications(true).build())
+            .defaultInputModes(List.of("text"))
+            .defaultOutputModes(List.of("text"))
+            .skills(List.of())
+            .build();
+
+    private final AtomicReference<GetTaskPushNotificationConfigRequest> receivedRequest = new AtomicReference<>();
+    private Server server;
+    private ManagedChannel channel;
+
+    @BeforeEach
+    void setUp() throws Exception {
+        String serverName = InProcessServerBuilder.generateName();
+        server = InProcessServerBuilder.forName(serverName)
+                .directExecutor()
+                .addService(new A2AServiceGrpc.A2AServiceImplBase() {
+                    @Override
+                    public void getTaskPushNotificationConfig(GetTaskPushNotificationConfigRequest request,
+                            StreamObserver<org.a2aproject.sdk.grpc.TaskPushNotificationConfig> responseObserver) {
+                        receivedRequest.set(request);
+                        responseObserver.onNext(org.a2aproject.sdk.grpc.TaskPushNotificationConfig.newBuilder()
+                                .setTaskId(request.getTaskId())
+                                .setId(request.getId().isEmpty() ? request.getTaskId() : request.getId())
+                                .setUrl(CALLBACK_URL)
+                                .build());
+                        responseObserver.onCompleted();
+                    }
+                })
+                .build()
+                .start();
+        channel = InProcessChannelBuilder.forName(serverName).directExecutor().build();
+    }
+
+    @AfterEach
+    void tearDown() throws InterruptedException {
+        channel.shutdownNow().awaitTermination(5, TimeUnit.SECONDS);
+        server.shutdownNow().awaitTermination(5, TimeUnit.SECONDS);
+    }
+
+    @Test
+    void testGetPushNotificationConfigWithOmittedId() throws Exception {
+        assertGetPushNotificationConfig(new GetTaskPushNotificationConfigParams(TASK_ID), null, "", "");
+    }
+
+    @Test
+    void testGetPushNotificationConfigWithOmittedIdViaBuilder() throws Exception {
+        assertGetPushNotificationConfig(GetTaskPushNotificationConfigParams.builder().taskId(TASK_ID).build(),
+                null, "", "");
+    }
+
+    @Test
+    void testGetPushNotificationConfigWithEmptyId() throws Exception {
+        assertGetPushNotificationConfig(new GetTaskPushNotificationConfigParams(TASK_ID, ""), null, "", "");
+    }
+
+    @Test
+    void testGetPushNotificationConfigWithExplicitIdAndDefaultTenant() throws Exception {
+        assertGetPushNotificationConfig(new GetTaskPushNotificationConfigParams(TASK_ID, "config-1"),
+                "default-tenant", "config-1", "default-tenant");
+    }
+
+    @Test
+    void testGetPushNotificationConfigWithOmittedIdAndRequestTenant() throws Exception {
+        assertGetPushNotificationConfig(new GetTaskPushNotificationConfigParams(TASK_ID, null, "request-tenant"),
+                "default-tenant", "", "request-tenant");
+    }
+
+    private void assertGetPushNotificationConfig(GetTaskPushNotificationConfigParams params,
+            @Nullable String defaultTenant, String expectedId, String expectedTenant) throws Exception {
+        GrpcTransport transport = new GrpcTransport(channel, CARD, defaultTenant, null);
+        TaskPushNotificationConfig result = transport.getTaskPushNotificationConfiguration(params, null);
+
+        GetTaskPushNotificationConfigRequest request = receivedRequest.get();
+        assertNotNull(request);
+        assertEquals(TASK_ID, request.getTaskId());
+        assertEquals(expectedId, request.getId());
+        assertEquals(expectedTenant, request.getTenant());
+        assertEquals(expectedId.isEmpty() ? TASK_ID : expectedId, result.id());
+        assertEquals(TASK_ID, result.taskId());
+        assertEquals(CALLBACK_URL, result.url());
+    }
+}

client/transport/rest/src/test/java/org/a2aproject/sdk/client/transport/rest/RestTransportTest.java

@@ -340,6 +340,33 @@ public void testGetTaskPushNotificationConfiguration() throws Exception {
         assertEquals("jwt", authenticationInfo.scheme());
     }
 
+    @Test
+    public void testGetTaskPushNotificationConfigurationWithOmittedId() throws Exception {
+        assertGetTaskPushNotificationConfigurationWithDefaultId(
+                new GetTaskPushNotificationConfigParams("de38c76d-d54c-436c-8b9f-4c2703648d64"));
+    }
+
+    @Test
+    public void testGetTaskPushNotificationConfigurationWithEmptyId() throws Exception {
+        assertGetTaskPushNotificationConfigurationWithDefaultId(
+                new GetTaskPushNotificationConfigParams("de38c76d-d54c-436c-8b9f-4c2703648d64", ""));
+    }
+
+    private void assertGetTaskPushNotificationConfigurationWithDefaultId(
+            GetTaskPushNotificationConfigParams params) throws Exception {
+        this.server.when(request()
+                        .withMethod("GET")
+                        .withPath("/tasks/de38c76d-d54c-436c-8b9f-4c2703648d64/pushNotificationConfigs/"))
+                .respond(response()
+                        .withStatusCode(200)
+                        .withBody(GET_TASK_PUSH_NOTIFICATION_CONFIG_TEST_RESPONSE));
+
+        RestTransport client = new RestTransport(CARD);
+        TaskPushNotificationConfig config = client.getTaskPushNotificationConfiguration(params, null);
+
+        assertEquals("https://example.com/callback", config.url());
+    }
+
     /**
      * Test of listTaskPushNotificationConfigurations method, of class JSONRestTransport.
      */