PiT 25.1: Quarkus dev mode fails with NoClassDefFoundError: JsonSerializeAs due to Jackson 2.x/3.x conflict

[manolo]

Description

Quarkus dev mode fails to start with NoClassDefFoundError: com/fasterxml/jackson/annotation/JsonSerializeAs when the Vaadin BOM is placed before the Quarkus BOM in dependencyManagement.

PiT (Platform in Test) reorders the BOMs so Vaadin BOM comes first. This is needed so that the Vaadin version under test takes precedence over the version pinned by Quarkus Platform. However, this causes Jackson 3.x (from Vaadin BOM/flow-server) to win over Jackson 2.x (from Quarkus BOM), breaking Vert.x which depends on Jackson 2.x.

Root cause

In Maven, the first BOM in dependencyManagement wins for version resolution:

• Vaadin BOM first (PiT order): flow-server brings tools.jackson.core:jackson-databind:3.0.4 (Jackson 3.x), which pulls com.fasterxml.jackson.core:jackson-annotations:2.20 as a bridge. Vert.x's DatabindCodec fails because JsonSerializeAs is not available.
• Quarkus BOM first (default order): Quarkus manages com.fasterxml.jackson.core:jackson-core:2.21.1 (Jackson 2.x), which is compatible with Vert.x.

The underlying issue is that flow-server depends on Jackson 3.x (tools.jackson.core), which is incompatible with Quarkus/Vert.x that uses Jackson 2.x. When both are on the classpath and Jackson 3.x wins resolution, the Vert.x classloader fails.

Dependency tree (relevant parts)

io.vertx:vertx-core:4.5.25
  \- com.fasterxml.jackson.core:jackson-core:jar:2.21.1:compile

com.vaadin:flow-server:25.0.7
  +- tools.jackson.core:jackson-core:jar:3.0.4:compile
  +- tools.jackson.core:jackson-databind:jar:3.0.4:compile
  |  \- com.fasterxml.jackson.core:jackson-annotations:jar:2.20:compile

Stack trace

ERROR [io.quarkus.deployment.dev.IsolatedDevModeMain] Failed to start quarkus:
  Build step io.quarkus.devui.deployment.BuildTimeContentProcessor#createBuildTimeConstJsTemplate
  threw an exception: java.lang.NoClassDefFoundError: com/fasterxml/jackson/annotation/JsonSerializeAs
    at io.vertx.core.json.jackson.DatabindCodec.<clinit>(DatabindCodec.java:36)
Caused by: java.lang.ClassNotFoundException: com.fasterxml.jackson.annotation.JsonSerializeAs

Steps to reproduce

mvn -ntp -q -B io.quarkus.platform:quarkus-maven-plugin:create \
  -Dextensions=rest,vaadin -DwithCodestart \
  -DprojectGroupId=com.vaadin.starter -DprojectArtifactId=vaadin-quarkus

cd vaadin-quarkus

Then swap the BOM order in pom.xml so vaadin-bom comes before quarkus-bom in <dependencyManagement>:

<dependencyManagement>
    <dependencies>
        <!-- Vaadin BOM first (triggers the bug) -->
        <dependency>
            <groupId>com.vaadin</groupId>
            <artifactId>vaadin-bom</artifactId>
            <version>${vaadin.version}</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
        <!-- Quarkus BOM second -->
        <dependency>
            <groupId>${quarkus.platform.group-id}</groupId>
            <artifactId>${quarkus.platform.artifact-id}</artifactId>
            <version>${quarkus.platform.version}</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
    </dependencies>
</dependencyManagement>

Then run:

mvn -Dquarkus.enforceBuildGoal=false quarkus:dev

With default BOM order (Quarkus first), it works fine.

Why this matters

PiT needs to reorder the BOMs to test newer Vaadin versions against a Quarkus project. Without the reorder, the Quarkus BOM pins the Vaadin version and PiT cannot test the target version. The vaadin-quarkus-extension should be able to handle both BOM orderings, or flow-server should not leak Jackson 3.x into the classpath in a way that conflicts with Jackson 2.x.

Environment

• Quarkus: 3.32.2
• Vaadin: 25.0.6 (flow-server 25.0.7)
• Java: 21
• OS: macOS / Linux (both affected)

[mcollovati]

This is a known issue with the latest Quarkus version, and I guess it could only be fixed by upgrading Flow to Jackson 3.1, since Jackson 3.0 depends on an older version of the Jackson annotation artifact.

[mcollovati]

In Flow, we are waiting for Spring Boot 4.0.4 that should also bump to Jackson 3.1 (vaadin/flow#23652)

[manolo]

Updated the issue, seems that the problem is when we swap the order of boms 🤔
Is that something that we should remove from our docs/scripts?

[mcollovati]

I remember previously swap was needed because of JNA clash. But nowadays Vaadin does not ship JNA transitively anymore, so the swap should be unnecessary.

[manolo]

The Vaadin Quarkus integration docs give contradictory advice on BOM ordering:

• The Getting Started section shows Quarkus BOM first (default generator order)
• The Known Issues section recommends putting Vaadin BOM first to fix JNA conflicts

Following the "Known Issues" advice is what triggers this Jackson conflict. In Maven, the first BOM wins version resolution, so putting Vaadin BOM first makes Jackson 3.x (tools.jackson.core) take precedence over Jackson 2.x (com.fasterxml.jackson), which breaks Vert.x/Quarkus.

The docs should either:

• Remove the advice to reorder BOMs (since it now causes a worse problem than the one it solves)
• Or suggest a targeted fix for JNA (explicit version override) instead of a blanket BOM reorder

[mcollovati]

The JNA part must be removed from the docs

[mcollovati]

I wonder if we should remove the whole "Known issues" section or just remove the JNA example and change the docs to say something like "If you experience problems with dependencies, you can try to swap the poms"

[manolo]

Let's keep the section, remove JNA not needed anymore, and mention in the case that you experiment problems ...

probably code block regarding this can be removed to avoid copy and paste issues