Java companion file handling for FW7 broken in new Eclipse

[ripla]

Steps to reproduce

1. Install Eclipse 2018-12 + Designer for Framework 7
2. Import FW7 project
3. Create a new FW7 design

Actual behavior

Design created without a companion file, with the exception:

java.lang.NoClassDefFoundError: org/eclipse/jdt/internal/corext/codemanipulation/StubUtility
	at com.vaadin.designer2.eclipse.java.ComponentJavaModel.formatJavaClass(ComponentJavaModel.java:268)
	at com.vaadin.designer2.eclipse.java.ComponentJavaModel.createJavaClassFromRoot(ComponentJavaModel.java:177)
	at com.vaadin.designer2.eclipse.wizards.NewDesignWizardPage.createJavaFile(NewDesignWizardPage.java:289)

Wizard stays open.

Expected behaviour

Companion file created normally.

IDE, Designer and OS version

Eclipse 2018-12, Designer for Framework 7 1.4.4, macOS & Ubuntu

Note

Affects all Java companion file operations, e.g. when saving an existing design.

[AlfredoDaAs]

working with vaadin 7, Eclipse 2018-12 and Designer for Framework 7 1.4.4, and I can't save.
OS version: Windows 10

java.lang.NoClassDefFoundError: org/eclipse/jdt/internal/corext/codemanipulation/StubUtility at com.vaadin.designer.eclipse.java.ComponentJavaModel.formatJavaClass(ComponentJavaModel.java:268) at com.vaadin.designer.eclipse.java.ComponentJavaModel.createJavaClassFromRoot(ComponentJavaModel.java:177) at com.vaadin.designer.eclipse.java.ComponentJavaModel.createJavaClassFromRoot(ComponentJavaModel.java:152)

@ripla is this only happening in Designer for framework 7? how long would this issue will take to be fixed?
this looks like the #1987

[ripla]

Yes, this is the same bug, but for the Framework 7 Designer. Unfortunately, the support for Framework 7 has ended, so we're not going to fix this bug. As a workaround, you can downgrade to an earlier Eclipse release.