[bean completion proposals] proposals should show up for empty prefix

[martinlippert]

Looks like the bean completion proposals do not show up (yet) when there is no prefix, e.g.

public class TestBean2 {

    public void foo() {
        <*>
    }

}

Would be nice if the bean proposals would show up in this case, too.

[BoykoAlex]

Fixed with 2512212