feat: enable self-signed JWTs by default in ServiceOptions

Author: whowes

java-bigquery/google-cloud-bigquery/src/main/java/com/google/cloud/bigquery/BigQueryOptions.java

@@ -213,6 +213,11 @@ public static HttpTransportOptions getDefaultHttpTransportOptions() {
     return HttpTransportOptions.newBuilder().setReadTimeout(DEFAULT_READ_API_TIME_OUT).build();
   }
 
+  @Override
+  protected boolean useSelfSignedJwt() {
+    return false;
+  }
+
   @Override
   protected Set<String> getScopes() {
     return SCOPES;

sdk-platform-java/java-core/google-cloud-core/src/main/java/com/google/cloud/ServiceOptions.java

@@ -650,9 +650,17 @@ public Credentials getScopedCredentials() {
         && ((GoogleCredentials) credentials).createScopedRequired()) {
       credentialsToReturn = ((GoogleCredentials) credentials).createScoped(getScopes());
     }
+    if (useSelfSignedJwt() && credentialsToReturn instanceof ServiceAccountCredentials) {
+      credentialsToReturn =
+          ((ServiceAccountCredentials) credentialsToReturn).createWithUseJwtAccessWithScope(true);
+    }
     return credentialsToReturn;
   }
 
+  protected boolean useSelfSignedJwt() {
+    return true;
+  }
+
   /** Returns configuration parameters for request retries. */
   public RetrySettings getRetrySettings() {
     return retrySettings;