a2aproject · ehsavoie · Feb 10, 2026
diff --git a/common/src/main/java/io/a2a/util/Assert.java b/common/src/main/java/io/a2a/util/Assert.java
@@ -1,5 +1,7 @@
 package io.a2a.util;
 
+import org.jspecify.annotations.Nullable;
+
 public final class Assert {
 
     /**
@@ -11,18 +13,21 @@ public final class Assert {
      * @return the value that was passed in
      * @throws IllegalArgumentException if the value is {@code null}
      */
-    @NotNull
-    public static <T> T checkNotNullParam(String name, T value) throws IllegalArgumentException {
+    public static <T> @NotNull T checkNotNullParam(String name, @Nullable T value) throws IllegalArgumentException {
         checkNotNullParamChecked("name", name);
-        checkNotNullParamChecked(name, value);
+        if (value == null) {
+            throw new IllegalArgumentException("Parameter '" + name + "' may not be null");
+        }
         return value;
     }
 
-    private static <T> void checkNotNullParamChecked(final String name, final T value) {
-        if (value == null) throw new IllegalArgumentException("Parameter '" + name + "' may not be null");
+    private static <T> void checkNotNullParamChecked(final String name, final @Nullable T value) {
+        if (value == null) {
+            throw new IllegalArgumentException("Parameter '" + name + "' may not be null");
+        }
     }
 
-    public static void isNullOrStringOrInteger(Object value) {
+    public static void isNullOrStringOrInteger(@Nullable Object value) {
         if (! (value == null || value instanceof String || value instanceof Integer)) {
             throw new IllegalArgumentException("Id must be null, a String, or an Integer");
         }

diff --git a/jsonrpc-common/src/main/java/io/a2a/jsonrpc/common/json/JsonUtil.java b/jsonrpc-common/src/main/java/io/a2a/jsonrpc/common/json/JsonUtil.java
@@ -22,15 +22,13 @@
 import java.time.OffsetDateTime;
 import java.time.format.DateTimeFormatter;
 import java.time.format.DateTimeParseException;
-import java.util.Map;
 import java.util.Set;
 
 import com.google.gson.Gson;
 import com.google.gson.GsonBuilder;
 import com.google.gson.JsonSyntaxException;
 import com.google.gson.ToNumberPolicy;
 import com.google.gson.TypeAdapter;
-import com.google.gson.reflect.TypeToken;
 import com.google.gson.stream.JsonReader;
 import com.google.gson.stream.JsonToken;
 import com.google.gson.stream.JsonWriter;
@@ -435,7 +433,7 @@ private A2AError createErrorInstance(@Nullable Integer code, @Nullable String me
                 case INVALID_AGENT_RESPONSE_ERROR_CODE ->
                     new InvalidAgentResponseError(code, message, data);
                 default ->
-                    new A2AError(code, message, data);
+                    new A2AError(code, message == null ? "" : message, data);
             };
         }
     }

diff --git a/reference/rest/src/main/java/io/a2a/server/rest/quarkus/A2AServerRoutes.java b/reference/rest/src/main/java/io/a2a/server/rest/quarkus/A2AServerRoutes.java
@@ -289,7 +289,9 @@ public void getTaskPushNotificationConfiguration(RoutingContext rc) {
         try {
             if (taskId == null || taskId.isEmpty()) {
                 response = jsonRestHandler.createErrorResponse(new InvalidParamsError("bad task id"));
-            } else {
+            } else if (configId == null || configId.isEmpty()) { 
+                response = jsonRestHandler.createErrorResponse(new InvalidParamsError("bad configuration id"));
+            }else {
                 response = jsonRestHandler.getTaskPushNotificationConfiguration(taskId, configId, extractTenant(rc), context);
             }
         } catch (Throwable t) {
@@ -299,26 +301,7 @@ public void getTaskPushNotificationConfiguration(RoutingContext rc) {
         }
     }
 
-    @Route(regex = "^\\/(?<tenant>[^\\/]*\\/?)tasks\\/(?<taskId>[^/]+)\\/pushNotificationConfigs\\/$", order = 1, methods = {Route.HttpMethod.GET}, type = Route.HandlerType.BLOCKING)
-    public void getTaskPushNotificationConfigurationWithoutId(RoutingContext rc) {
-        String taskId = rc.pathParam("taskId");
-        ServerCallContext context = createCallContext(rc, GET_TASK_PUSH_NOTIFICATION_CONFIG_METHOD);
-        HTTPRestResponse response = null;
-        try {
-            if (taskId == null || taskId.isEmpty()) {
-                response = jsonRestHandler.createErrorResponse(new InvalidParamsError("bad task id"));
-            } else {
-                // Call get with null configId - trailing slash distinguishes this from list
-                response = jsonRestHandler.getTaskPushNotificationConfiguration(taskId, null, extractTenant(rc), context);
-            }
-        } catch (Throwable t) {
-            response = jsonRestHandler.createErrorResponse(new InternalError(t.getMessage()));
-        } finally {
-            sendResponse(rc, response);
-        }
-    }
-
-    @Route(regex = "^\\/(?<tenant>[^\\/]*\\/?)tasks\\/(?<taskId>[^/]+)\\/pushNotificationConfigs", order = 3, methods = {Route.HttpMethod.GET}, type = Route.HandlerType.BLOCKING)
+    @Route(regex = "^\\/(?<tenant>[^\\/]*\\/?)tasks\\/(?<taskId>[^/]+)\\/pushNotificationConfigs\\/?$", order = 3, methods = {Route.HttpMethod.GET}, type = Route.HandlerType.BLOCKING)
     public void listTaskPushNotificationConfigurations(RoutingContext rc) {
         String taskId = rc.pathParam("taskId");
         ServerCallContext context = createCallContext(rc, LIST_TASK_PUSH_NOTIFICATION_CONFIG_METHOD);

diff --git a/server-common/src/main/java/io/a2a/server/agentexecution/RequestContext.java b/server-common/src/main/java/io/a2a/server/agentexecution/RequestContext.java
@@ -99,14 +99,12 @@ public RequestContext(
         if (params != null) {
             if (taskId != null && !taskId.equals(params.message().taskId())) {
                 throw new InvalidParamsError("bad task id");
-            } else {
-                checkOrGenerateTaskId();
             }
+            this.taskId = checkOrGenerateTaskId();
             if (contextId != null && !contextId.equals(params.message().contextId())) {
                 throw new InvalidParamsError("bad context id");
-            } else {
-                checkOrGenerateContextId();
             }
+            this.contextId = checkOrGenerateContextId();
         }
     }
 
@@ -246,9 +244,9 @@ public void attachRelatedTask(Task task) {
         relatedTasks.add(task);
     }
 
-    private void checkOrGenerateTaskId() {
+    private @Nullable String checkOrGenerateTaskId() {
         if (params == null) {
-            return;
+            return taskId;
         }
         if (taskId == null && params.message().taskId() == null) {
             // Message is immutable, create new one with generated taskId
@@ -257,15 +255,17 @@ private void checkOrGenerateTaskId() {
                     .taskId(generatedTaskId)
                     .build();
             params = new MessageSendParams(updatedMessage, params.configuration(), params.metadata());
-            this.taskId = generatedTaskId;
-        } else if (params.message().taskId() != null) {
-            this.taskId = params.message().taskId();
+            return generatedTaskId;
+        } 
+        if (params.message().taskId() != null) {
+            return params.message().taskId();
         }
+        return taskId;
     }
 
-    private void checkOrGenerateContextId() {
+    private @Nullable String checkOrGenerateContextId() {
         if (params == null) {
-            return;
+            return contextId;
         }
         if (contextId == null && params.message().contextId() == null) {
             // Message is immutable, create new one with generated contextId
@@ -274,10 +274,12 @@ private void checkOrGenerateContextId() {
                     .contextId(generatedContextId)
                     .build();
             params = new MessageSendParams(updatedMessage, params.configuration(), params.metadata());
-            this.contextId = generatedContextId;
-        } else if (params.message().contextId() != null) {
-            this.contextId = params.message().contextId();
+            return generatedContextId;
+        } 
+        if (params.message().contextId() != null) {
+            return params.message().contextId();
         }
+        return contextId;
     }
 
     private String getMessageText(Message message, String delimiter) {

diff --git a/server-common/src/main/java/io/a2a/server/requesthandlers/DefaultRequestHandler.java b/server-common/src/main/java/io/a2a/server/requesthandlers/DefaultRequestHandler.java
@@ -487,7 +487,8 @@ public EventKind onMessageSend(MessageSendParams params, ServerCallContext conte
 
             // Store push notification config for newly created tasks (mirrors streaming logic)
             // Only for NEW tasks - existing tasks are handled by initMessageSend()
-            if (mss.task() == null && kind instanceof Task createdTask && shouldAddPushInfo(params)) {
+            if (mss.task() == null && kind instanceof Task createdTask && pushConfigStore != null 
+                    && params.configuration() != null && params.configuration().pushNotificationConfig() != null) {
                 LOGGER.debug("Storing push notification config for new task {} (original taskId from params: {})",
                         createdTask.id(), params.message().taskId());
                 pushConfigStore.setInfo(createdTask.id(), params.configuration().pushNotificationConfig());
@@ -565,7 +566,7 @@ public EventKind onMessageSend(MessageSendParams params, ServerCallContext conte
                     kind = updatedTask;
                     LOGGER.debug("DefaultRequestHandler: Step 5 - Fetched current task for {} with state {} and {} artifacts",
                         taskId.get(), updatedTask.status().state(),
-                        updatedTask.artifacts().size());
+                        updatedTask.artifacts() != null ? updatedTask.artifacts().size() : 0);
                 } else {
                     LOGGER.warn("DefaultRequestHandler: Step 5 - Task {} not found in TaskStore!", taskId.get());
                 }
@@ -626,7 +627,7 @@ public Flow.Publisher<StreamingEventKind> onMessageSendStream(
         // Store push notification config SYNCHRONOUSLY for new tasks before agent starts
         // This ensures config is available when MainEventBusProcessor sends push notifications
         // For existing tasks, config is stored in initMessageSend()
-        if (mss.task() == null && shouldAddPushInfo(params)) {
+        if (mss.task() == null && pushConfigStore != null && params.configuration() != null && params.configuration().pushNotificationConfig() != null) {
             // Satisfy Nullaway
             Objects.requireNonNull(taskId.get(), "taskId was null");
             LOGGER.debug("Storing push notification config for new streaming task {} EARLY (original taskId from params: {})",
@@ -863,10 +864,6 @@ public void onDeleteTaskPushNotificationConfig(
         pushConfigStore.deleteInfo(params.id(), params.pushNotificationConfigId());
     }
 
-    private boolean shouldAddPushInfo(MessageSendParams params) {
-        return pushConfigStore != null && params.configuration() != null && params.configuration().pushNotificationConfig() != null;
-    }
-
     /**
      * Register and execute the agent asynchronously in the agent-executor thread pool.
      *
@@ -1014,7 +1011,7 @@ private MessageSendSetup initMessageSend(MessageSendParams params, ServerCallCon
             LOGGER.debug("Found task updating with message {}", params.message());
             task = taskManager.updateWithMessage(params.message(), task);
 
-            if (shouldAddPushInfo(params)) {
+            if (pushConfigStore != null && params.configuration() != null && params.configuration().pushNotificationConfig() != null) {
                 LOGGER.debug("Adding push info");
                 pushConfigStore.setInfo(task.id(), params.configuration().pushNotificationConfig());
             }

diff --git a/server-common/src/main/java/io/a2a/server/tasks/AgentEmitter.java b/server-common/src/main/java/io/a2a/server/tasks/AgentEmitter.java
@@ -18,6 +18,7 @@
 import io.a2a.spec.TaskStatus;
 import io.a2a.spec.TaskStatusUpdateEvent;
 import io.a2a.spec.TextPart;
+import io.a2a.util.Assert;
 import org.jspecify.annotations.Nullable;
 
 /**
@@ -95,8 +96,8 @@
  */
 public class AgentEmitter {
     private final EventQueue eventQueue;
-    private final @Nullable String taskId;
-    private final @Nullable String contextId;
+    private final String taskId;
+    private final String contextId;
     private final AtomicBoolean terminalStateReached = new AtomicBoolean(false);
 
     /**
@@ -107,8 +108,8 @@ public class AgentEmitter {
      */
     public AgentEmitter(RequestContext context, EventQueue eventQueue) {
         this.eventQueue = eventQueue;
-        this.taskId = context.getTaskId();
-        this.contextId = context.getContextId();
+         this.taskId = Assert.checkNotNullParam("taskId",context.getTaskId());
+        this.contextId = Assert.checkNotNullParam("contextId",context.getContextId());
     }
 
     private void updateStatus(TaskState taskState) {

diff --git a/server-common/src/main/java/io/a2a/server/tasks/BasePushNotificationSender.java b/server-common/src/main/java/io/a2a/server/tasks/BasePushNotificationSender.java
@@ -78,7 +78,7 @@ public void sendNotification(StreamingEventKind event) {
         String nextPageToken = null;
         do {
           ListTaskPushNotificationConfigResult pageResult = configStore.getInfo(new ListTaskPushNotificationConfigParams(taskId,
-              DEFAULT_PAGE_SIZE, nextPageToken, ""));
+              DEFAULT_PAGE_SIZE, nextPageToken == null ? "" : nextPageToken, ""));
           if (!pageResult.configs().isEmpty()) {
             configs.addAll(pageResult.configs());
           }
@@ -111,11 +111,14 @@ public void sendNotification(StreamingEventKind event) {
     protected @Nullable String extractTaskId(StreamingEventKind event) {
         if (event instanceof Task task) {
             return task.id();
-        } else if (event instanceof Message message) {
+        }
+        if (event instanceof Message message) {
             return message.taskId();
-        } else if (event instanceof TaskStatusUpdateEvent statusUpdate) {
+        }
+        if (event instanceof TaskStatusUpdateEvent statusUpdate) {
             return statusUpdate.taskId();
-        } else if (event instanceof TaskArtifactUpdateEvent artifactUpdate) {
+        }
+        if (event instanceof TaskArtifactUpdateEvent artifactUpdate) {
             return artifactUpdate.taskId();
         }
         throw new IllegalStateException("Unknown StreamingEventKind: " + event);

diff --git a/server-common/src/main/java/io/a2a/server/tasks/InMemoryPushNotificationConfigStore.java b/server-common/src/main/java/io/a2a/server/tasks/InMemoryPushNotificationConfigStore.java
@@ -41,7 +41,7 @@ public PushNotificationConfig setInfo(String taskId, PushNotificationConfig noti
         Iterator<PushNotificationConfig> notificationConfigIterator = notificationConfigList.iterator();
         while (notificationConfigIterator.hasNext()) {
             PushNotificationConfig config = notificationConfigIterator.next();
-            if (config.id().equals(notificationConfig.id())) {
+            if (config.id() != null  && config.id().equals(notificationConfig.id())) {
                 notificationConfigIterator.remove();
                 break;
             }