Can't Compile WidgetSet - Vaadin 7 Java 12

Vaadin 6 / 7 / 8
1

When we try to build our UI it fails when trying to compile the widgetset. We just switched from Java 8 to 12. We are building with Gradle 5. Any help would be appreciated.

Looks like a transitive dependency has changed.

Error Log:
[INFO]
Compiling module com.dmb.ui.widgetset.Ui_projectWidgetset
[ERROR]
Hint: Check that your module inherits ‘com.google.gwt.core.Core’ either directly or indirectly (most often by inheriting module ‘com.google.gwt.user.User’)

Build Output:

Task :ManagerUI:vaadinCompile FAILED

FAILURE: Build failed with an exception.

  • What went wrong:
    Execution failed for task ‘:ManagerUI:vaadinCompile’.

Widgetset failed to compile. See error log.

— boilerplate output —

BUILD FAILED in 1m 29s
71 actionable tasks: 32 executed, 39 up-to-date

org.gradle.internal.exceptions.LocationAwareException: Execution failed for task ‘:ManagerUI:vaadinCompile’.
more…

2

I’m betting that I need to find out which version of GWT Vaadin 7.7.9 (what we are using) needs. Luckily we will soon be upgrading to Vaadin 13 or newer.

3

Vaadin 7.7.9 was depending on GWT 2.7.0 which does not contain the class that the WidgetSetCompiler is looking for. Why this only shows up when you build with Java 12 I don’t know.