fix: update GDCH audience error message to be more descriptive

Author: diegomarquezp

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

@@ -250,7 +250,7 @@ static GdchCredentials fromPkcs8(String privateKeyPkcs8, GdchCredentials.Builder
   @ObsoleteApi("Use createWithGdchAudience(String) instead.")
   public GdchCredentials createWithGdchAudience(URI apiAudience) {
     Preconditions.checkNotNull(
-        apiAudience, "Audience are not configured for GDCH service account credentials.");
+        apiAudience, "Audience cannot be null or empty for GDCH service account credentials.");
     return this.toBuilder().setGdchAudience(apiAudience.toString()).build();
   }
 
@@ -262,7 +262,7 @@ public GdchCredentials createWithGdchAudience(URI apiAudience) {
   public GdchCredentials createWithGdchAudience(String apiAudience) {
     if (Strings.isNullOrEmpty(apiAudience)) {
       throw new IllegalArgumentException(
-          "Audience are not configured for GDCH service account credentials.");
+          "Audience cannot be null or empty for GDCH service account credentials.");
     }
     return this.toBuilder().setGdchAudience(apiAudience).build();
   }
@@ -278,8 +278,8 @@ public GdchCredentials createWithGdchAudience(String apiAudience) {
   public AccessToken refreshAccessToken() throws IOException {
     Preconditions.checkNotNull(
         this.apiAudience,
-        "Audience are not configured for GDCH service account. Specify the "
-            + "audience by calling createWithGDCHAudience.");
+        "Audience cannot be null or empty for GDCH service account credentials. "
+            + "Specify the audience by calling createWithGdchAudience.");
 
     JsonFactory jsonFactory = GsonFactory.getDefaultInstance();
 

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

@@ -525,7 +525,7 @@ void createWithGdchAudience_nullApiAudience() throws IOException {
         assertThrows(
             IllegalArgumentException.class,
             () -> credentials.createWithGdchAudience((String) null));
-    assertTrue(ex.getMessage().contains("Audience are not configured for GDCH service account"));
+    assertTrue(ex.getMessage().contains("Audience cannot be null or empty for GDCH service account"));
   }
 
   @Test
@@ -545,7 +545,7 @@ void createWithGdchAudience_emptyApiAudience() throws IOException {
         assertThrows(
             IllegalArgumentException.class,
             () -> credentials.createWithGdchAudience(""));
-    assertTrue(ex.getMessage().contains("Audience are not configured for GDCH service account"));
+    assertTrue(ex.getMessage().contains("Audience cannot be null or empty for GDCH service account"));
   }
 
   @Test
@@ -664,8 +664,8 @@ void refreshAccessToken_nullApiAudience() throws IOException {
       assertTrue(
           ex.getMessage()
               .contains(
-                  "Audience are not configured for GDCH service account. Specify the "
-                      + "audience by calling createWithGDCHAudience"));
+                  "Audience cannot be null or empty for GDCH service account credentials. "
+                      + "Specify the audience by calling createWithGdchAudience"));
     }
   }