Frequently Asked Questions

April 23, 2026 · View on GitHub

My app uses the async client libraries but never gets any results

Cause: Reactive types (Mono<T>, Flux<T>) are cold — they do nothing until subscribed to.

// WRONG — subscribes but may exit before results arrive
Mono<Response<Key>> result = asyncClient.getKey();
result.subscribe(response -> System.out.println(response.getValue()));

// CORRECT — block() ensures the result is received before moving on
asyncClient.getKey()
    .subscribe(response -> System.out.println(response.getValue()))
    .block();

// OR — use the synchronous client directly
Key key = client.getKey();

Note: .block() is only appropriate in non-reactive applications (e.g. command-line tools). In a fully reactive pipeline, propagate Mono/Flux to the caller.

I'm getting `NoSuchMethodError` or `NoClassDefFoundError`

This almost always means a dependency version conflict.

Diagnosis

mvn dependency:tree

Find the package that contains the missing type. Look for multiple versions in the tree.

Resolution

Force a specific version in your project's pom.xml:

<dependency>
  <groupId>com.example</groupId>
  <artifactId>conflicting-library</artifactId>
  <version>2.14.3</version> <!-- force the version both libraries are compatible with -->
</dependency>

See Troubleshoot dependency version conflicts for a detailed walkthrough.

Creating Shaded JARs to Avoid Dependency Conflicts

Shaded JARs bundle and relocate all dependencies, eliminating transitive conflicts. The Maven Shade Plugin (maven-shade-plugin) is the standard tool for this.

How to Manage Dependencies on Azure Databricks (ADB)

ADB injects Spark and its dependencies (including older Jackson versions) into the app classpath, causing conflicts with Azure SDK dependencies.

Recommended solution: Create a shaded JAR (see above), then upload it as a cluster library or job JAR.

Steps

Create a shaded JAR with relocation rules for conflicting packages (e.g. Jackson) using maven-shade-plugin.
In the Azure Portal → Databricks workspace → create a cluster.
From the cluster, create a Job → set task as "Set JAR" → upload your shaded JAR.
Set the Main class to the mainClass entry from the maven-shade-plugin configuration.

If conflicts persist: Add relocation rules for each conflicting dependency in the shade plugin configuration.

My App Uses Java's Security Manager and I Have All Permissions But Still Get Denied

Cause: The Azure SDK uses MSAL4J for authentication, which calls CompletableFuture internally. This uses threads from the common ForkJoinPool, and those threads have no permissions by default under a Security Manager.

Fix 1: Use a custom `ExecutorService` (preferred for azure-identity ≥ 1.1.0)

ExecutorService executor = Executors.newCachedThreadPool();
try {
    ClientSecretCredential credential = new ClientSecretCredentialBuilder()
        .clientId("<client-ID>")
        .clientSecret("<client-secret>")
        .tenantId("<tenant-ID>")
        .executorService(executor)  // <-- provide your thread pool
        .build();

    SecretClient secretClient = new SecretClientBuilder()
        .vaultUrl("https://<vault>.vault.azure.net")
        .credential(credential)
        .buildClient();

    KeyVaultSecret secret = secretClient.getSecret("<secret-name>");
} finally {
    executor.shutdown();
}

Fix 2: Custom `ForkJoinWorkerThreadFactory`

public static class MyForkJoinWorkerThreadFactory
        implements ForkJoinPool.ForkJoinWorkerThreadFactory {
    public final ForkJoinWorkerThread newThread(ForkJoinPool pool) {
        return new ForkJoinWorkerThread(pool) {};
    }
}

Then add this JVM argument:

-Djava.util.concurrent.ForkJoinPool.common.threadFactory=MyForkJoinWorkerThreadFactory