EDIT

Moving to additivity milestone. But in general remembering of expansion state currently does not work correctly in the TaxEditor and should be fixed soon.

This should be fixed now. Please review.

When testing on TaxonDescriptions I got an CCE:

last remote method : http://test.e-taxonomy.eu:80/cdmserver/rem_conf_am/remoting/description.service
last remote request client time : 2020-06-03T12:22:45.598
last remote request response header time : Wed, 03 Jun 2020 12:22:46 GMT
client error time : 2020-06-03T12:22:45.864
login : admin
editor version : 5.15.0.202006022252
server : test.e-taxonomy.eu (edit-test) / rem_conf_am
schema version : 5.15.0.0.20200510
os : Windows Server 2012 R2 6.3 amd64
java : 1.8.0_121
org.eclipse.e4.core.di.InjectionException: java.lang.ClassCastException: eu.etaxonomy.cdm.model.description.TaxonDescription cannot be cast to eu.etaxonomy.cdm.model.description.SpecimenDescription
    at org.eclipse.e4.core.internal.di.MethodRequestor.execute(MethodRequestor.java:65)
    at org.eclipse.e4.core.internal.di.InjectorImpl.invokeUsingClass(InjectorImpl.java:282)
    at org.eclipse.e4.core.internal.di.InjectorImpl.invoke(InjectorImpl.java:264)
    at org.eclipse.e4.core.contexts.ContextInjectionFactory.invoke(ContextInjectionFactory.java:132)
    at org.eclipse.e4.core.commands.internal.HandlerServiceHandler.execute(HandlerServiceHandler.java:152)
    at org.eclipse.core.commands.Command.executeWithChecks(Command.java:494)
    at org.eclipse.core.commands.ParameterizedCommand.executeWithChecks(ParameterizedCommand.java:488)
    at org.eclipse.e4.core.commands.internal.HandlerServiceImpl.executeHandler(HandlerServiceImpl.java:210)
    at org.eclipse.e4.ui.workbench.renderers.swt.HandledContributionItem.executeItem(HandledContributionItem.java:433)
    at org.eclipse.e4.ui.workbench.renderers.swt.AbstractContributionItem.handleWidgetSelection(AbstractContributionItem.java:454)
    at org.eclipse.e4.ui.workbench.renderers.swt.AbstractContributionItem$3.handleEvent(AbstractContributionItem.java:482)
    at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)
    at org.eclipse.swt.widgets.Display.sendEvent(Display.java:4418)
    at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1079)
    at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:4236)
    at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3824)
    at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$4.run(PartRenderingEngine.java:1121)
    at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:336)
    at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.run(PartRenderingEngine.java:1022)
    at org.eclipse.e4.ui.internal.workbench.E4Workbench.createAndRunUI(E4Workbench.java:150)
    at org.eclipse.ui.internal.Workbench$5.run(Workbench.java:693)
    at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:336)
    at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:610)
    at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:148)
    at eu.etaxonomy.taxeditor.Application.start(Application.java:20)
    at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:196)
    at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:134)
    at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:104)
    at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:388)
    at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:243)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:673)
    at org.eclipse.equinox.launcher.Main.basicRun(Main.java:610)
    at org.eclipse.equinox.launcher.Main.run(Main.java:1519)
Caused by: java.lang.ClassCastException: eu.etaxonomy.cdm.model.description.TaxonDescription cannot be cast to eu.etaxonomy.cdm.model.description.SpecimenDescription
    at eu.etaxonomy.taxeditor.editor.view.descriptive.e4.handler.DeleteHandlerE4.execute(DeleteHandlerE4.java:166)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.eclipse.e4.core.internal.di.MethodRequestor.execute(MethodRequestor.java:55)
    ... 36 more

this should be fixed now.

works now