Make GCP SA token refresh non-blocking with warning on failure

Port of Go SDK #1544. The GCP SA access token
(X-Databricks-GCP-SA-Access-Token) refresh is now non-blocking in both
GoogleIdCredentialsProvider and GoogleCredentialsCredentialsProvider.
On failure, a warning is logged and the header is skipped instead of
throwing an exception. The token is also now always attempted regardless
of client type (not just for ACCOUNT clients).

Co-authored-by: Isaac

Author: hectorcast-db

databricks-sdk-java/src/main/java/com/databricks/sdk/core/GoogleCredentialsCredentialsProvider.java

@@ -66,17 +66,12 @@ public HeaderFactory configure(DatabricksConfig config) {
       Map<String, String> headers = new HashMap<>();
       headers.put("Authorization", String.format("Bearer %s", idToken.getTokenValue()));
 
-      if (config.getClientType() == ClientType.ACCOUNT) {
-        AccessToken token;
-        try {
-          token = finalServiceAccountCredentials.createScoped(GCP_SCOPES).refreshAccessToken();
-        } catch (IOException e) {
-          String message =
-              "Failed to refresh access token from Google service account credentials.";
-          LOG.error(message + e);
-          throw new DatabricksException(message, e);
-        }
+      try {
+        AccessToken token =
+            finalServiceAccountCredentials.createScoped(GCP_SCOPES).refreshAccessToken();
         headers.put(SA_ACCESS_TOKEN_HEADER, token.getTokenValue());
+      } catch (IOException e) {
+        LOG.warn("Failed to refresh GCP SA access token, skipping header: {}", e.getMessage());
       }
 
       return headers;

databricks-sdk-java/src/main/java/com/databricks/sdk/core/GoogleIdCredentialsProvider.java

@@ -69,15 +69,11 @@ public HeaderFactory configure(DatabricksConfig config) {
         throw new DatabricksException(message, e);
       }
 
-      if (config.getClientType() == ClientType.ACCOUNT) {
-        try {
-          headers.put(
-              SA_ACCESS_TOKEN_HEADER, gcpScopedCredentials.refreshAccessToken().getTokenValue());
-        } catch (IOException e) {
-          String message = "Failed to refresh access token from scoped id token credentials.";
-          LOG.error(message + e);
-          throw new DatabricksException(message, e);
-        }
+      try {
+        headers.put(
+            SA_ACCESS_TOKEN_HEADER, gcpScopedCredentials.refreshAccessToken().getTokenValue());
+      } catch (IOException e) {
+        LOG.warn("Failed to refresh GCP SA access token, skipping header: {}", e.getMessage());
       }
 
       return headers;