The Class File Viewer cannot handle the given input ('org.eclipse.ui.ide.FileStoreEditorInput').

If one drag&drop a classfile into eclipse from an external location the editor fails:

```
org.eclipse.core.runtime.CoreException: The Class File Viewer cannot handle the given input ('org.eclipse.ui.ide.FileStoreEditorInput').
at org.eclipse.jdt.internal.ui.javaeditor.ClassFileEditor.doSetInput(ClassFileEditor.java:663)
at org.eclipse.ui.texteditor.AbstractTextEditor.lambda$1(AbstractTextEditor.java:3162)
at org.eclipse.jface.operation.ModalContext.runInCurrentThread(ModalContext.java:434)
at org.eclipse.jface.operation.ModalContext.run(ModalContext.java:352)
at org.eclipse.ui.internal.WorkbenchWindow.lambda$7(WorkbenchWindow.java:2345)
at org.eclipse.swt.custom.BusyIndicator.showWhile(BusyIndicator.java:74)
at org.eclipse.ui.internal.WorkbenchWindow.run(WorkbenchWindow.java:2343)
at org.eclipse.ui.texteditor.AbstractTextEditor.internalInit(AbstractTextEditor.java:3179)
at org.eclipse.ui.texteditor.AbstractTextEditor.init(AbstractTextEditor.java:3204)
at org.eclipse.ui.internal.EditorReference.initialize(EditorReference.java:353)
at org.eclipse.ui.internal.e4.compatibility.CompatibilityPart.create(CompatibilityPart.java:344)
at jdk.internal.reflect.GeneratedMethodAccessor99.invoke(Unknown Source)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
```

I don't see a compelling reason why the file must be in the workspace to be displayed, so it seems the editor simply not handles the `FileStoreEditorInput`.