migrating GWT2.8.2 to 2.12.2 , GWT version and plugin both

[Ism]

Request for Help: Migrating GWT 2.8.2 → 2.12.2 (Plugin + Version)

We are in the process of migrating our project from GWT 2.8.2 to GWT 2.12.2, including switching from the old Mojo plugin to the new .

• With GWT 2.8.2 + Mojo plugin, everything has worked fine for several years.

• After configuring the new plugin, we are running into issues.

Project Structure

Main Application Module com.test.Application.gwt.xml

This module inherits third-party JARs that contain both sources and their own .gwt.xml files:

<module> <inherits name="com.thirdparty.T1"/> </module>

Third-Party JAR (T1) Structure:

Code

src/main/java 

 └── com/thirdparty/... 

              └── T1.gwt.xml

Contents of T1.gwt.xml:

<module> <source path=""/> </module>

Problem

When migrating, compilation fails with:

Code

[ERROR] Line 40: No source code is available

Attempts so far:

• Tried <source path=""/>

• Tried <super-source path=""/>

Both approaches fail with the same error.

Question

How should we correctly configure the tbroyer gwt-maven-plugin and module definitions so that third-party JARs with embedded sources and .gwt.xml files are properly recognized under GWT 2.12.2?

[Thomas Broyer]

I'm afraid you're not providing enough information for us to help.

First, I'm assuming you read https://tbroyer.github.io/gwt-maven-plugin/migrating.html, as well as https://tbroyer.github.io/gwt-maven-plugin/index.html and https://tbroyer.github.io/gwt-maven-plugin/usage.html. If you haven't already, I'd suggest studying the structure of a project generated from the gwt-maven-archetypes: https://github.com/tbroyer/gwt-maven-archetypes/ or the e2e project used in tests (https://github.com/tbroyer/gwt-maven-plugin/tree/main/src/it/e2e)

How's your code organized in your project? Is the client code in a separate project from the server code? Or both in the same project?

How did you configure the net.ltgt.gwt.maven:gwt-maven-plugin? How was the CodeHaus Mojo plugin configured?

You're mentioning src/main/java in the structure of "Third-Party JAR (T1)", does it mean it's a project in the same Maven reactor build? Or is it really a third-party JAR and it actually doesn't have a src/main/java?

The best way to troubleshoot is to run with debug logs (mvn -X) and look for two lines starting with "Classpath:" and "Arguments:" respectively. You can also compare their content vs. the content of the two lines starting with "Execute command" and "With CLASSPATH" emitted by the CodeHaus Mojo plugin in the debug logs.

[RobW]

Just checked our files - we just have the following in that area:

    <source path="client" />
    <!-- the below seems to be needed to help resolving ImageResource annotations -->
    <resource path="public" />

We follow the normal ./client, ./server, ./public structure from way back when GWT started.

[Craig Mitchell]

I don't have any source path.  All I have is the "inherits".

Eg:  I use Elemental2, which has a Core.gwt.xml file in the elemental2.core package in the jar (in the Core.gwt.xml, it has <source path=""/>)

All I had to do was add it in my client pom.xml:

<dependency>
  <groupId>com.google.elemental2</groupId>
  <artifactId>elemental2-core</artifactId>
  <version>${elemental2.version}</version>
</dependency>

And add the inherits in my module.gwt.xml file:

<inherits name="elemental2.core.Core"/>

And everything works great.

[Ismail Shaik]

Thank you all for the quick response.

I followed exactly how described in the plugin page. now getting java.util.Calender, org.hibernate.Hibernate etc missing.Do i need to   add additional for gwt2.12?

Please note we are also upgrading GXT4.0.X to 4.2.X along with Gwt2.8.2 to 2.12.2 . ofcourse pluginmigrating.

working configuration for smae codebase: Gwt2.8.2, Gxt4.0.2 and mojo plugin 2.8.2. i will try to mask share the code

thanks

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Thanks
Ismail

[Craig Mitchell]

java.util.Calender is not an emulated class in GWT.  You cannot use it in the client.  I would guess org.hibernate.Hibernate is the same.

Is the code that uses these classes meant to be in your server module (not your client or shared module)?

[Thomas Broyer]

On Monday, November 24, 2025 at 7:17:18 PM UTC+1 Ism wrote:

Thank you all for the quick response.

I followed exactly how described in the plugin page. now getting java.util.Calender, org.hibernate.Hibernate etc missing.Do i need to   add additional for gwt2.12?

Please note we are also upgrading GXT4.0.X to 4.2.X along with Gwt2.8.2 to 2.12.2 . ofcourse pluginmigrating.

Can't you first migrate the plugin without any code change, and then do the other upgrades?

The latest version of net.ltgt.gwt.maven:gwt-maven-plugin should be compatible with GWT 2.8.2.