vaadin noob

I was trying to add default app layout but my IDE doesn’t even understand what getTabs() method mean. Maybe some of us could help me?
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That’s not all source code of the example. See the left button on the top right

The discoverability of that button is very bad, that has been noted. I’ll try to find the time to implement a better design for it.

Would text “Show full code” be too long?