feat: use Credentials' request metadata to populate headers

Instead of manually adding an authorization header and potentially
omitting other necessary metadata (such as x-goog-user-project) copy
all the necessary headers managed by the Credentials object into the
request.

PiperOrigin-RevId: 852263160

Author: google-genai-bot

core/src/main/java/com/google/adk/tools/applicationintegrationtoolset/ApplicationIntegrationToolset.java

@@ -8,9 +8,8 @@
 import com.google.adk.agents.ReadonlyContext;
 import com.google.adk.tools.BaseTool;
 import com.google.adk.tools.BaseToolset;
-import com.google.adk.tools.applicationintegrationtoolset.IntegrationConnectorTool.DefaultHttpExecutor;
-import com.google.adk.tools.applicationintegrationtoolset.IntegrationConnectorTool.HttpExecutor;
 import io.reactivex.rxjava3.core.Flowable;
+import java.net.http.HttpClient;
 import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.List;
@@ -30,7 +29,8 @@ public class ApplicationIntegrationToolset implements BaseToolset {
   @Nullable String toolNamePrefix;
   @Nullable String toolInstructions;
   public static final ObjectMapper OBJECT_MAPPER = new ObjectMapper();
-  HttpExecutor httpExecutor;
+  private final HttpClient httpClient;
+  private final CredentialsHelper credentialsHelper;
 
   /**
    * ApplicationIntegrationToolset generates tools from a given Application Integration resource.
@@ -85,7 +85,8 @@ public ApplicationIntegrationToolset(
         serviceAccountJson,
         toolNamePrefix,
         toolInstructions,
-        new DefaultHttpExecutor().createExecutor(serviceAccountJson));
+        HttpClient.newHttpClient(),
+        new GoogleCredentialsHelper());
   }
 
   ApplicationIntegrationToolset(
@@ -99,7 +100,8 @@ public ApplicationIntegrationToolset(
       String serviceAccountJson,
       String toolNamePrefix,
       String toolInstructions,
-      HttpExecutor httpExecutor) {
+      HttpClient httpClient,
+      CredentialsHelper credentialsHelper) {
     this.project = project;
     this.location = location;
     this.integration = integration;
@@ -110,7 +112,8 @@ public ApplicationIntegrationToolset(
     this.serviceAccountJson = serviceAccountJson;
     this.toolNamePrefix = toolNamePrefix;
     this.toolInstructions = toolInstructions;
-    this.httpExecutor = httpExecutor;
+    this.httpClient = httpClient;
+    this.credentialsHelper = credentialsHelper;
   }
 
   List<String> getPathUrl(String openApiSchemaString) throws Exception {
@@ -145,7 +148,9 @@ private List<BaseTool> getAllTools() throws Exception {
               null,
               null,
               null,
-              this.httpExecutor);
+              this.serviceAccountJson,
+              this.httpClient,
+              this.credentialsHelper);
       openApiSchemaString = integrationClient.generateOpenApiSpec();
       List<String> pathUrls = getPathUrl(openApiSchemaString);
       for (String pathUrl : pathUrls) {
@@ -161,7 +166,8 @@ private List<BaseTool> getAllTools() throws Exception {
                   null,
                   null,
                   this.serviceAccountJson,
-                  this.httpExecutor));
+                  this.httpClient,
+                  this.credentialsHelper));
         }
       }
     } else if (!isNullOrEmpty(this.connection)
@@ -175,7 +181,9 @@ private List<BaseTool> getAllTools() throws Exception {
               this.connection,
               this.entityOperations,
               this.actions,
-              this.httpExecutor);
+              this.serviceAccountJson,
+              this.httpClient,
+              this.credentialsHelper);
       ObjectNode parentOpenApiSpec = OBJECT_MAPPER.createObjectNode();
       ObjectNode openApiSpec =
           integrationClient.getOpenApiSpecForConnection(toolNamePrefix, toolInstructions);
@@ -188,7 +196,14 @@ private List<BaseTool> getAllTools() throws Exception {
         if (!isNullOrEmpty(toolName)) {
           ConnectionsClient connectionsClient =
               new ConnectionsClient(
-                  this.project, this.location, this.connection, this.httpExecutor, OBJECT_MAPPER);
+                  this.project,
+                  this.location,
+                  this.connection,
+                  this.serviceAccountJson,
+                  this.httpClient,
+                  this.credentialsHelper,
+                  OBJECT_MAPPER);
+
           ConnectionsClient.ConnectionDetails connectionDetails =
               connectionsClient.getConnectionDetails();
 
@@ -202,7 +217,8 @@ private List<BaseTool> getAllTools() throws Exception {
                   connectionDetails.serviceName,
                   connectionDetails.host,
                   this.serviceAccountJson,
-                  this.httpExecutor));
+                  this.httpClient,
+                  this.credentialsHelper));
         }
       }
     } else {

core/src/main/java/com/google/adk/tools/applicationintegrationtoolset/ConnectionsClient.java

@@ -4,11 +4,13 @@
 
 import com.fasterxml.jackson.core.type.TypeReference;
 import com.fasterxml.jackson.databind.ObjectMapper;
-import com.google.adk.tools.applicationintegrationtoolset.IntegrationConnectorTool.HttpExecutor;
+import com.google.auth.Credentials;
+import com.google.common.base.Preconditions;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import java.io.IOException;
 import java.net.URI;
+import java.net.http.HttpClient;
 import java.net.http.HttpRequest;
 import java.net.http.HttpResponse;
 import java.util.HashMap;
@@ -28,7 +30,9 @@ public class ConnectionsClient {
   private final String location;
   private final String connection;
   private static final String CONNECTOR_URL = "https://connectors.googleapis.com";
-  private final HttpExecutor httpExecutor;
+  private final HttpClient httpClient;
+  private final String serviceAccountJson;
+  private final CredentialsHelper credentialsHelper;
   private final ObjectMapper objectMapper;
 
   /** Represents details of a connection. */
@@ -63,13 +67,34 @@ public ConnectionsClient(
       String project,
       String location,
       String connection,
-      HttpExecutor httpExecutor,
+      String serviceAccountJson,
+      HttpClient httpClient,
+      CredentialsHelper credentialsHelper,
       ObjectMapper objectMapper) {
+
     this.project = project;
     this.location = location;
     this.connection = connection;
-    this.httpExecutor = httpExecutor;
+    this.httpClient = Preconditions.checkNotNull(httpClient);
     this.objectMapper = objectMapper;
+    this.serviceAccountJson = serviceAccountJson;
+    this.credentialsHelper = Preconditions.checkNotNull(credentialsHelper);
+  }
+
+  public ConnectionsClient(
+      String project,
+      String location,
+      String connection,
+      HttpClient httpClient,
+      ObjectMapper objectMapper) {
+    this(
+        project,
+        location,
+        connection,
+        null,
+        httpClient,
+        new GoogleCredentialsHelper(),
+        objectMapper);
   }
 
   /**
@@ -173,16 +198,17 @@ public ActionSchema getActionSchema(String action) throws IOException, Interrupt
   }
 
   private HttpResponse<String> executeApiCall(String url) throws IOException, InterruptedException {
-    HttpRequest request =
+    HttpRequest.Builder requestBuilder =
         HttpRequest.newBuilder()
             .uri(URI.create(url))
             .header("Content-Type", "application/json")
-            .header("Authorization", "Bearer " + httpExecutor.getToken())
-            .GET()
-            .build();
+            .GET();
+
+    Credentials credentials = credentialsHelper.getGoogleCredentials(serviceAccountJson);
+    requestBuilder = CredentialsHelper.populateHeaders(requestBuilder, credentials);
 
     HttpResponse<String> response =
-        httpExecutor.send(request, HttpResponse.BodyHandlers.ofString());
+        httpClient.send(requestBuilder.build(), HttpResponse.BodyHandlers.ofString());
 
     if (response.statusCode() >= 400) {
       String body = response.body();

core/src/main/java/com/google/adk/tools/applicationintegrationtoolset/CredentialsHelper.java

@@ -0,0 +1,46 @@
+package com.google.adk.tools.applicationintegrationtoolset;
+
+import com.google.auth.Credentials;
+import java.io.IOException;
+import java.net.http.HttpRequest;
+import java.util.List;
+import java.util.Map;
+import javax.annotation.Nullable;
+
+/**
+ * This interface provides a method to convert a service account JSON string to a Google Credentials
+ * object.
+ *
+ * <p>Additionally, contains helper methods that aid with transfering the credentials' data to the
+ * HttpRequest.Builder object
+ */
+public interface CredentialsHelper {
+
+  /**
+   * Converts a service account JSON string to a Google Credentials object.
+   *
+   * @param serviceAccountJson The service account JSON string.
+   * @return A Google Credentials object.
+   * @throws IOException when an error occurs during the conversion.
+   */
+  Credentials getGoogleCredentials(@Nullable String serviceAccountJson) throws IOException;
+
+  /**
+   * Populates the headers (such as Authorization or x-goog-project) in the HttpRequest.Builder with
+   * the metadata from the credentials.
+   *
+   * @param builder HttpRequest.Builder object to populate the headers
+   * @param credentials Credentials object containing the metadata
+   * @return HttpRequest.Builder object with the headers populated
+   * @throws IOException if an error occurs when getting the metadata from the credentials
+   */
+  public static HttpRequest.Builder populateHeaders(
+      HttpRequest.Builder builder, Credentials credentials) throws IOException {
+    for (Map.Entry<String, List<String>> entry : credentials.getRequestMetadata().entrySet()) {
+      for (String value : entry.getValue()) {
+        builder = builder.header(entry.getKey(), value);
+      }
+    }
+    return builder;
+  }
+}

core/src/main/java/com/google/adk/tools/applicationintegrationtoolset/GoogleCredentialsHelper.java

@@ -0,0 +1,30 @@
+package com.google.adk.tools.applicationintegrationtoolset;
+
+import static java.nio.charset.StandardCharsets.UTF_8;
+
+import com.google.auth.oauth2.GoogleCredentials;
+import com.google.auth.oauth2.ServiceAccountCredentials;
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import javax.annotation.Nullable;
+
+public final class GoogleCredentialsHelper implements CredentialsHelper {
+
+  @Override
+  public GoogleCredentials getGoogleCredentials(@Nullable String serviceAccountJson)
+      throws IOException {
+    GoogleCredentials credentials;
+
+    if (serviceAccountJson != null && !serviceAccountJson.isBlank()) {
+      try (InputStream is = new ByteArrayInputStream(serviceAccountJson.getBytes(UTF_8))) {
+        credentials = ServiceAccountCredentials.fromStream(is);
+      }
+    } else {
+      credentials = GoogleCredentials.getApplicationDefault();
+    }
+    credentials = credentials.createScoped("https://www.googleapis.com/auth/cloud-platform");
+    credentials.refreshIfExpired();
+    return credentials;
+  }
+}