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fix: Setting the proper content type for errors. #720

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Merged
kabir merged 1 commit into from
Mar 10, 2026
Merged

fix: Setting the proper content type for errors. #720

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7 changes: 7 additions & 0 deletions common/src/main/java/io/a2a/common/MediaType.java
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Original file line number Diff line number Diff line change
@@ -0,0 +1,7 @@
package io.a2a.common;

public interface MediaType {

public static final String APPLICATION_JSON = "application/json";
public static final String APPLICATION_PROBLEM_JSON = "application/problem+json";
}
5 changes: 3 additions & 2 deletions reference/jsonrpc/src/main/java/io/a2a/server/apps/quarkus/A2AServerRoutes.java
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@@ -1,5 +1,6 @@
package io.a2a.server.apps.quarkus;

import static io.a2a.common.MediaType.APPLICATION_PROBLEM_JSON;
import static io.a2a.server.ServerCallContext.TRANSPORT_KEY;
import static io.a2a.transport.jsonrpc.context.JSONRPCContextKeys.HEADERS_KEY;
import static io.a2a.transport.jsonrpc.context.JSONRPCContextKeys.METHOD_NAME_KEY;
Expand Down Expand Up @@ -134,7 +135,7 @@ public void invokeJSONRPCHandler(@Body String body, RoutingContext rc) {
if (error != null) {
rc.response()
.setStatusCode(200)
.putHeader(CONTENT_TYPE, APPLICATION_JSON)
.putHeader(CONTENT_TYPE, APPLICATION_PROBLEM_JSON)
.end(serializeResponse(error));
} else if (streaming) {
final Multi<? extends A2AResponse<?>> finalStreamingResponse = streamingResponse;
Expand All @@ -150,7 +151,7 @@ public void invokeJSONRPCHandler(@Body String body, RoutingContext rc) {
} else {
rc.response()
.setStatusCode(200)
.putHeader(CONTENT_TYPE, APPLICATION_JSON)
.putHeader(CONTENT_TYPE, nonStreamingResponse.getError() != null ? APPLICATION_PROBLEM_JSON : APPLICATION_JSON)
.end(serializeResponse(nonStreamingResponse));
}
}
Expand Down
58 changes: 50 additions & 8 deletions reference/jsonrpc/src/test/java/io/a2a/server/apps/quarkus/A2AServerRoutesTest.java
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@@ -1,11 +1,21 @@
package io.a2a.server.apps.quarkus;

import static io.a2a.common.MediaType.APPLICATION_PROBLEM_JSON;
import static io.a2a.spec.A2AMethods.DELETE_TASK_PUSH_NOTIFICATION_CONFIG_METHOD;
import static io.a2a.spec.A2AMethods.GET_TASK_METHOD;
import static io.a2a.spec.A2AMethods.GET_TASK_PUSH_NOTIFICATION_CONFIG_METHOD;
import static io.a2a.spec.A2AMethods.LIST_TASK_PUSH_NOTIFICATION_CONFIG_METHOD;
import static io.a2a.spec.A2AMethods.SEND_MESSAGE_METHOD;
import static io.a2a.spec.A2AMethods.SET_TASK_PUSH_NOTIFICATION_CONFIG_METHOD;
import static io.a2a.spec.A2AMethods.SUBSCRIBE_TO_TASK_METHOD;
import static io.a2a.spec.A2AMethods.CANCEL_TASK_METHOD;
import static io.a2a.spec.A2AMethods.GET_EXTENDED_AGENT_CARD_METHOD;
import static io.a2a.spec.A2AMethods.SEND_STREAMING_MESSAGE_METHOD;
import static io.a2a.transport.jsonrpc.context.JSONRPCContextKeys.METHOD_NAME_KEY;
import static io.a2a.transport.jsonrpc.context.JSONRPCContextKeys.TENANT_KEY;
import static java.util.Collections.singletonList;
import static io.vertx.core.http.HttpHeaders.CONTENT_TYPE;
import static jakarta.ws.rs.core.MediaType.APPLICATION_JSON;
import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertNotNull;
import static org.mockito.ArgumentMatchers.any;
Expand Down Expand Up @@ -59,14 +69,6 @@
import org.junit.jupiter.api.Test;
import org.mockito.ArgumentCaptor;

import static io.a2a.spec.A2AMethods.DELETE_TASK_PUSH_NOTIFICATION_CONFIG_METHOD;
import static io.a2a.spec.A2AMethods.GET_TASK_METHOD;
import static io.a2a.spec.A2AMethods.GET_TASK_PUSH_NOTIFICATION_CONFIG_METHOD;
import static io.a2a.spec.A2AMethods.LIST_TASK_PUSH_NOTIFICATION_CONFIG_METHOD;
import static io.a2a.spec.A2AMethods.SEND_MESSAGE_METHOD;
import static io.a2a.spec.A2AMethods.SET_TASK_PUSH_NOTIFICATION_CONFIG_METHOD;
import static io.a2a.spec.A2AMethods.SUBSCRIBE_TO_TASK_METHOD;

/**
* Unit test for JSON-RPC A2AServerRoutes that verifies the method names are properly set
* in the ServerCallContext for all request types.
Expand Down Expand Up @@ -166,6 +168,7 @@ public void testSendMessage_MethodNameSetInContext() {
ServerCallContext capturedContext = contextCaptor.getValue();
assertNotNull(capturedContext);
assertEquals(SEND_MESSAGE_METHOD, capturedContext.getState().get(METHOD_NAME_KEY));
verify(mockHttpResponse).putHeader(CONTENT_TYPE, APPLICATION_JSON);
}

@Test
Expand Down Expand Up @@ -250,6 +253,7 @@ public void testGetTask_MethodNameSetInContext() {
ServerCallContext capturedContext = contextCaptor.getValue();
assertNotNull(capturedContext);
assertEquals(GET_TASK_METHOD, capturedContext.getState().get(METHOD_NAME_KEY));
verify(mockHttpResponse).putHeader(CONTENT_TYPE, APPLICATION_JSON);
}

@Test
Expand Down Expand Up @@ -286,6 +290,7 @@ public void testCancelTask_MethodNameSetInContext() {
ServerCallContext capturedContext = contextCaptor.getValue();
assertNotNull(capturedContext);
assertEquals(CANCEL_TASK_METHOD, capturedContext.getState().get(METHOD_NAME_KEY));
verify(mockHttpResponse).putHeader(CONTENT_TYPE, APPLICATION_JSON);
}

@Test
Expand Down Expand Up @@ -363,6 +368,7 @@ public void testCreateTaskPushNotificationConfig_MethodNameSetInContext() {
ServerCallContext capturedContext = contextCaptor.getValue();
assertNotNull(capturedContext);
assertEquals(SET_TASK_PUSH_NOTIFICATION_CONFIG_METHOD, capturedContext.getState().get(METHOD_NAME_KEY));
verify(mockHttpResponse).putHeader(CONTENT_TYPE, APPLICATION_JSON);
}

@Test
Expand Down Expand Up @@ -401,6 +407,7 @@ public void testGetTaskPushNotificationConfig_MethodNameSetInContext() {
ServerCallContext capturedContext = contextCaptor.getValue();
assertNotNull(capturedContext);
assertEquals(GET_TASK_PUSH_NOTIFICATION_CONFIG_METHOD, capturedContext.getState().get(METHOD_NAME_KEY));
verify(mockHttpResponse).putHeader(CONTENT_TYPE, APPLICATION_JSON);
}

@Test
Expand Down Expand Up @@ -440,6 +447,7 @@ public void testListTaskPushNotificationConfig_MethodNameSetInContext() {
ServerCallContext capturedContext = contextCaptor.getValue();
assertNotNull(capturedContext);
assertEquals(LIST_TASK_PUSH_NOTIFICATION_CONFIG_METHOD, capturedContext.getState().get(METHOD_NAME_KEY));
verify(mockHttpResponse).putHeader(CONTENT_TYPE, APPLICATION_JSON);
}

@Test
Expand Down Expand Up @@ -473,6 +481,7 @@ public void testDeleteTaskPushNotificationConfig_MethodNameSetInContext() {
ServerCallContext capturedContext = contextCaptor.getValue();
assertNotNull(capturedContext);
assertEquals(DELETE_TASK_PUSH_NOTIFICATION_CONFIG_METHOD, capturedContext.getState().get(METHOD_NAME_KEY));
verify(mockHttpResponse).putHeader(CONTENT_TYPE, APPLICATION_JSON);
}

@Test
Expand Down Expand Up @@ -509,6 +518,7 @@ public void testGetExtendedCard_MethodNameSetInContext() {
ServerCallContext capturedContext = contextCaptor.getValue();
assertNotNull(capturedContext);
assertEquals(GET_EXTENDED_AGENT_CARD_METHOD, capturedContext.getState().get(METHOD_NAME_KEY));
verify(mockHttpResponse).putHeader(CONTENT_TYPE, APPLICATION_JSON);
}

@Test
Expand Down Expand Up @@ -707,6 +717,38 @@ public void testTenantExtraction_StreamingRequest() {
assertEquals("myTenant/api", capturedContext.getState().get(TENANT_KEY));
}

@Test
public void testJsonParseError_ContentTypeIsProblemJson() {
// Arrange - invalid JSON
String invalidJson = "not valid json {{{";
when(mockRequestBody.asString()).thenReturn(invalidJson);

// Act
routes.invokeJSONRPCHandler(invalidJson, mockRoutingContext);

// Assert
verify(mockHttpResponse).putHeader(CONTENT_TYPE, APPLICATION_PROBLEM_JSON);
}

@Test
public void testMethodNotFound_ContentTypeIsProblemJson() {
// Arrange - unknown method
String jsonRpcRequest = """
{
"jsonrpc": "2.0",
"id": "cd4c76de-d54c-436c-8b9f-4c2703648d64",
"method": "UnknownMethod",
"params": {}
}""";
when(mockRequestBody.asString()).thenReturn(jsonRpcRequest);

// Act
routes.invokeJSONRPCHandler(jsonRpcRequest, mockRoutingContext);

// Assert
verify(mockHttpResponse).putHeader(CONTENT_TYPE, APPLICATION_PROBLEM_JSON);
}

/**
* Helper method to set a field via reflection for testing purposes.
*/
Expand Down
15 changes: 9 additions & 6 deletions transport/rest/src/main/java/io/a2a/transport/rest/handler/RestHandler.java
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@@ -1,5 +1,7 @@
package io.a2a.transport.rest.handler;

import static io.a2a.common.MediaType.APPLICATION_JSON;
import static io.a2a.common.MediaType.APPLICATION_PROBLEM_JSON;
import static io.a2a.server.util.async.AsyncUtils.createTubeConfig;
import static io.a2a.spec.A2AErrorCodes.JSON_PARSE_ERROR_CODE;

Expand Down Expand Up @@ -72,6 +74,7 @@ public class RestHandler {
private static final Logger log = Logger.getLogger(RestHandler.class.getName());
private static final String TASK_STATE_PREFIX = "TASK_STATE_";


// Fields set by constructor injection cannot be final. We need a noargs constructor for
// Jakarta compatibility, and it seems that making fields set by constructor injection
// final, is not proxyable in all runtimes
Expand Down Expand Up @@ -311,7 +314,7 @@ public HTTPRestResponse deleteTaskPushNotificationConfiguration(ServerCallContex
}
DeleteTaskPushNotificationConfigParams params = new DeleteTaskPushNotificationConfigParams(taskId, configId, tenant);
requestHandler.onDeleteTaskPushNotificationConfig(params, context);
return new HTTPRestResponse(204, "application/json", "");
return new HTTPRestResponse(204, APPLICATION_JSON, "");
} catch (A2AError e) {
return createErrorResponse(e);
} catch (Throwable throwable) {
Expand Down Expand Up @@ -344,8 +347,8 @@ private void validate(String json) {
private HTTPRestResponse createSuccessResponse(int statusCode, com.google.protobuf.Message.Builder builder) {
try {
// Include default value fields to ensure empty arrays, zeros, etc. are present in JSON
String jsonBody = JsonFormat.printer().includingDefaultValueFields().print(builder);
return new HTTPRestResponse(statusCode, "application/json", jsonBody);
String jsonBody = JsonFormat.printer().alwaysPrintFieldsWithNoPresence().print(builder);
return new HTTPRestResponse(statusCode, APPLICATION_JSON, jsonBody);
} catch (InvalidProtocolBufferException e) {
return createErrorResponse(new InternalError("Failed to serialize response: " + e.getMessage()));
}
Expand All @@ -358,7 +361,7 @@ public HTTPRestResponse createErrorResponse(A2AError error) {

private HTTPRestResponse createErrorResponse(int statusCode, A2AError error) {
String jsonBody = new HTTPRestErrorResponse(error).toJson();
return new HTTPRestResponse(statusCode, "application/json", jsonBody);
return new HTTPRestResponse(statusCode, APPLICATION_PROBLEM_JSON, jsonBody);
}

private HTTPRestStreamingResponse createStreamingResponse(Flow.Publisher<StreamingEventKind> publisher) {
Expand Down Expand Up @@ -467,7 +470,7 @@ public HTTPRestResponse getExtendedAgentCard(ServerCallContext context, String t
if (!agentCard.capabilities().extendedAgentCard() || extendedAgentCard == null || !extendedAgentCard.isResolvable()) {
throw new ExtendedAgentCardNotConfiguredError(null, "Extended Card not configured", null);
}
return new HTTPRestResponse(200, "application/json", JsonUtil.toJson(extendedAgentCard.get()));
return new HTTPRestResponse(200, APPLICATION_JSON, JsonUtil.toJson(extendedAgentCard.get()));
} catch (A2AError e) {
return createErrorResponse(e);
} catch (Throwable t) {
Expand All @@ -477,7 +480,7 @@ public HTTPRestResponse getExtendedAgentCard(ServerCallContext context, String t

public HTTPRestResponse getAgentCard() {
try {
return new HTTPRestResponse(200, "application/json", JsonUtil.toJson(agentCard));
return new HTTPRestResponse(200, APPLICATION_JSON, JsonUtil.toJson(agentCard));
} catch (Throwable t) {
return createErrorResponse(500, new InternalError(t.getMessage()));
}
Expand Down
18 changes: 9 additions & 9 deletions transport/rest/src/test/java/io/a2a/transport/rest/handler/RestHandlerTest.java
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Expand Up @@ -54,7 +54,7 @@ public void testGetTaskNotFound() {
RestHandler.HTTPRestResponse response = handler.getTask(callContext, "", "nonexistent", 0);

Assertions.assertEquals(404, response.getStatusCode());
Assertions.assertEquals("application/json", response.getContentType());
Assertions.assertEquals("application/problem+json", response.getContentType());
Assertions.assertTrue(response.getBody().contains("TaskNotFoundError"));
}

Expand All @@ -79,7 +79,7 @@ public void testListTasksInvalidStatus() {
null, null, null);

Assertions.assertEquals(422, response.getStatusCode());
Assertions.assertEquals("application/json", response.getContentType());
Assertions.assertEquals("application/problem+json", response.getContentType());
Assertions.assertTrue(response.getBody().contains("InvalidParamsError"));
}

Expand Down Expand Up @@ -122,7 +122,7 @@ public void testSendMessageInvalidBody() {
RestHandler.HTTPRestResponse response = handler.sendMessage(callContext, "", invalidBody);

Assertions.assertEquals(400, response.getStatusCode());
Assertions.assertEquals("application/json", response.getContentType());
Assertions.assertEquals("application/problem+json", response.getContentType());
Assertions.assertTrue(response.getBody().contains("JSONParseError"),response.getBody());
}

Expand All @@ -146,7 +146,7 @@ public void testSendMessageWrongValueBody() {
RestHandler.HTTPRestResponse response = handler.sendMessage(callContext, "", requestBody);

Assertions.assertEquals(422, response.getStatusCode());
Assertions.assertEquals("application/json", response.getContentType());
Assertions.assertEquals("application/problem+json", response.getContentType());
Assertions.assertTrue(response.getBody().contains("InvalidParamsError"));
}

Expand All @@ -157,7 +157,7 @@ public void testSendMessageEmptyBody() {
RestHandler.HTTPRestResponse response = handler.sendMessage(callContext, "", "");

Assertions.assertEquals(400, response.getStatusCode());
Assertions.assertEquals("application/json", response.getContentType());
Assertions.assertEquals("application/problem+json", response.getContentType());
Assertions.assertTrue(response.getBody().contains("InvalidRequestError"));
}

Expand Down Expand Up @@ -190,7 +190,7 @@ public void testCancelTaskNotFound() {
RestHandler.HTTPRestResponse response = handler.cancelTask(callContext, "", requestBody, "nonexistent");

Assertions.assertEquals(404, response.getStatusCode());
Assertions.assertEquals("application/json", response.getContentType());
Assertions.assertEquals("application/problem+json", response.getContentType());
Assertions.assertTrue(response.getBody().contains("TaskNotFoundError"));
}

Expand Down Expand Up @@ -564,7 +564,7 @@ public void testExtensionSupportRequiredErrorOnSendMessage() {
RestHandler.HTTPRestResponse response = handler.sendMessage(callContext, "", requestBody);

Assertions.assertEquals(400, response.getStatusCode());
Assertions.assertEquals("application/json", response.getContentType());
Assertions.assertEquals("application/problem+json", response.getContentType());
Assertions.assertTrue(response.getBody().contains("ExtensionSupportRequiredError"));
Assertions.assertTrue(response.getBody().contains("https://example.com/test-extension"));
}
Expand Down Expand Up @@ -764,7 +764,7 @@ public void testVersionNotSupportedErrorOnSendMessage() {
RestHandler.HTTPRestResponse response = handler.sendMessage(contextWithVersion, "", requestBody);

Assertions.assertEquals(501, response.getStatusCode());
Assertions.assertEquals("application/json", response.getContentType());
Assertions.assertEquals("application/problem+json", response.getContentType());
Assertions.assertTrue(response.getBody().contains("VersionNotSupportedError"));
Assertions.assertTrue(response.getBody().contains("2.0"));
}
Expand Down Expand Up @@ -969,7 +969,7 @@ public void testListTasksNegativeTimestampReturns422() {
null, "-1", null);

Assertions.assertEquals(422, response.getStatusCode());
Assertions.assertEquals("application/json", response.getContentType());
Assertions.assertEquals("application/problem+json", response.getContentType());
Assertions.assertTrue(response.getBody().contains("InvalidParamsError"));
}

Expand Down