Theme/Widgetset compilation fails in Eclipse, JDK17

[SteveDemy]

Theme and Widgetset compilation: The Java 17 JVM won't start due to use of the newly prohibited option "MaxPermSize" in the compilation scripts.

Unrecognized VM option 'MaxPermSize=512M'

Can those scripts (presumably in the Vaadin plugin for Eclipse) be upgraded? Or is there a way for the developer to access/override them?

[TatuLund]

Vaadin 8 widgetset code supports only upto Java 8 syntax with GWT 2.8.2.

If you override Vaadin 8 project to use GWT 2.9.0, as is done in this example https://github.com/TatuLund/gwt290-demo, you can use Java 11 also in widgetset code.

Generally speaking, JDK17 is not officially suppored with Vaadin 8.

[SteveDemy]

Thanks Tatu. The GWT 2.9.0 solution is outside the scope of my current problem. I don't need any modern Java in widgets, rather I've taken Java 17 into use in my development environment, including in Eclipse. With Java 16, both the theme and the widgetsets compile perfectly using the Eclipse IDE icons, albeit with a warning about ignoring the old "MaxPermSize" VM argument. The breaking change in JDK 17 is that the "MaxPermSize" argument prevents startup of the VM during both theme and widgetset compilation. If I could just remove that argument from each of those two scripts, I'd be in business. Is there a way to do that? Obviously the other solution is to keep JDK16 on the machine and revert to it during theme and widgetset compilation. But that's an awkward workflow. Is there a place I can see/modify or copy and manually run the scripts included in the Vaadin plugin for Eclipse?

[TatuLund]

Is there a place I can see/modify or copy and manually run the scripts included in the Vaadin plugin for Eclipse?

It seems not to be easily configurable.

However with vaadin-maven-plugin those can be adjusted fairly easily, example

            <plugin>
                <groupId>com.vaadin</groupId>
                <artifactId>vaadin-maven-plugin</artifactId>
                <configuration>
                    <extraJvmArgs>-Xmx512M -Xss1024k</extraJvmArgs>
                    <webappDirectory>${basedir}/target/classes/VAADIN/widgetsets</webappDirectory>
                    <draftCompile>false</draftCompile>
                    <compileReport>false</compileReport>
                    <style>OBF</style>
                    <strict>true</strict>
                </configuration>
                <executions>
                    <execution>
                        <goals>
                            <goal>update-theme</goal>
                            <!-- Comment out compile-theme goal to use on-the-fly theme compilation -->
                            <goal>compile-theme</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>