chore: address review comments for PR #1896

Author: diegomarquezp

oauth2_http/java/com/google/auth/oauth2/GdchCredentials.java

@@ -75,8 +75,16 @@ public class GdchCredentials extends GoogleCredentials {
   private static final LoggerProvider LOGGER_PROVIDER =
       LoggerProvider.forClazz(GdchCredentials.class);
   private static final String PARSE_ERROR_PREFIX = "Error parsing token refresh response. ";
-  @VisibleForTesting static final String SUPPORTED_FORMAT_VERSION = "1";
 
+  /**
+   * The expected format version for GDCH credential profiles.
+   * Version "1" indicates the initial and currently supported JSON format for these credentials.
+   * See go/gdch-python-auth-lib for more info.
+   */
+  @VisibleForTesting static final String SUPPORTED_JSON_FORMAT_VERSION = "1";
+
+  // Custom URN used by GDCH to identify service account tokens in token exchange requests.
+  // See go/gdch-python-auth-lib for more information.
   private static final String SERVICE_ACCOUNT_TOKEN_TYPE =
       "urn:k8s:params:oauth:token-type:serviceaccount";
 
@@ -198,9 +206,9 @@ static GdchCredentials fromJson(Map<String, Object> json, HttpTransportFactory t
         validateField((String) json.get("token_uri"), "token_uri");
     String caCertPath = (String) json.get("ca_cert_path");
 
-    if (!SUPPORTED_FORMAT_VERSION.equals(formatVersion)) {
+    if (!SUPPORTED_JSON_FORMAT_VERSION.equals(formatVersion)) {
       throw new IOException(
-          String.format("Only format version %s is supported.", SUPPORTED_FORMAT_VERSION));
+          String.format("Only format version %s is supported.", SUPPORTED_JSON_FORMAT_VERSION));
     }
 
     URI tokenServerUriFromCreds = null;
@@ -247,10 +255,8 @@ static GdchCredentials fromPkcs8(String privateKeyPkcs8, GdchCredentials.Builder
    */
   @ObsoleteApi("Use createWithGdchAudience(String) instead.")
   public GdchCredentials createWithGdchAudience(URI apiAudience) {
-    if (apiAudience == null) {
-      throw new IllegalArgumentException(
-          "Audience cannot be null or empty for GDCH service account credentials.");
-    }
+    Preconditions.checkNotNull(
+        apiAudience, "Audience are not configured for GDCH service account credentials.");
     return this.toBuilder().setGdchAudience(apiAudience.toString()).build();
   }
 
@@ -372,6 +378,9 @@ static String getIssuerSubjectValue(String projectId, String serviceIdentityName
     return String.format("system:serviceaccount:%s:%s", projectId, serviceIdentityName);
   }
 
+  /**
+   * @return the projectId set in the GDCH SA Key file or the user set projectId
+   */
   @Override
   public final String getProjectId() {
     return projectId;
@@ -571,16 +580,7 @@ public Builder setGdchAudience(String apiAudience) {
       return this;
     }
 
-    @CanIgnoreReturnValue
-    @ObsoleteApi("Use setGdchAudience(String) instead")
-    public Builder setGdchAudience(URI apiAudience) {
-      if (apiAudience == null) {
-        throw new IllegalArgumentException(
-            "Audience cannot be null for GDCH service account credentials.");
-      }
-      this.apiAudience = apiAudience.toString();
-      return this;
-    }
+
 
     public String getProjectId() {
       return projectId;

oauth2_http/javatests/com/google/auth/oauth2/DefaultCredentialsProviderTest.java

@@ -83,7 +83,7 @@ class DefaultCredentialsProviderTest {
   private static final String SA_PRIVATE_KEY_ID = "d84a4fefcf50791d4a90f2d7af17469d6282df9d";
   private static final String SA_PRIVATE_KEY_PKCS8 =
       ServiceAccountCredentialsTest.PRIVATE_KEY_PKCS8;
-  private static final String GDCH_SA_FORMAT_VERSION = GdchCredentials.SUPPORTED_FORMAT_VERSION;
+  private static final String GDCH_SA_FORMAT_VERSION = GdchCredentials.SUPPORTED_JSON_FORMAT_VERSION;
   private static final String GDCH_SA_PROJECT_ID = "gdch-service-account-project-id";
   private static final String GDCH_SA_PRIVATE_KEY_ID = "d84a4fefcf50791d4a90f2d7af17469d6282df9d";
   private static final String GDCH_SA_PRIVATE_KEY_PKC8 = GdchCredentialsTest.PRIVATE_KEY_PKCS8;

oauth2_http/javatests/com/google/auth/oauth2/GdchCredentialsTest.java

@@ -67,7 +67,7 @@
 
 /** Test case for {@link GdchCredentials}. */
 class GdchCredentialsTest extends BaseSerializationTest {
-  private static final String FORMAT_VERSION = GdchCredentials.SUPPORTED_FORMAT_VERSION;
+  private static final String FORMAT_VERSION = GdchCredentials.SUPPORTED_JSON_FORMAT_VERSION;
   private static final String PRIVATE_KEY_ID = "d84a4fefcf50791d4a90f2d7af17469d6282df9d";
   static final String PRIVATE_KEY_PKCS8 =
       "-----BEGIN PRIVATE KEY-----\n"
@@ -1201,14 +1201,7 @@ void builder_setGdchAudience_nullString() {
             .contains("Audience cannot be null or empty for GDCH service account credentials."));
   }
 
-  @Test
-  void builder_setGdchAudience_nullUri() {
-    GdchCredentials.Builder builder = GdchCredentials.newBuilder();
-    IllegalArgumentException ex =
-        assertThrows(IllegalArgumentException.class, () -> builder.setGdchAudience((URI) null));
-    assertTrue(
-        ex.getMessage().contains("Audience cannot be null for GDCH service account credentials."));
-  }
+
 
   static GenericJson writeGdchServiceAccountJson(
       String formatVersion,

oauth2_http/javatests/com/google/auth/oauth2/GoogleCredentialsTest.java

@@ -71,7 +71,7 @@ class GoogleCredentialsTest extends BaseSerializationTest {
   private static final String SA_PRIVATE_KEY_ID = "d84a4fefcf50791d4a90f2d7af17469d6282df9d";
   private static final String SA_PRIVATE_KEY_PKCS8 =
       ServiceAccountCredentialsTest.PRIVATE_KEY_PKCS8;
-  private static final String GDCH_SA_FORMAT_VERSION = GdchCredentials.SUPPORTED_FORMAT_VERSION;
+  private static final String GDCH_SA_FORMAT_VERSION = GdchCredentials.SUPPORTED_JSON_FORMAT_VERSION;
   private static final String GDCH_SA_PROJECT_ID = "gdch-service-account-project-id";
   private static final String GDCH_SA_PRIVATE_KEY_ID = "d84a4fefcf50791d4a90f2d7af17469d6282df9d";
   private static final String GDCH_SA_PRIVATE_KEY_PKC8 = GdchCredentialsTest.PRIVATE_KEY_PKCS8;