Method return type to fulfill multiple interfaces

Is it possible to specify a method which returns a object that implements two or multiple interfaces?

Say we have the following interfaces:

interface FooBar {
    [Foo] & [Bar] getFooBar();
}

interface Foo {
    void doFoo();
}

inteface Bar {
    void doBar();
}

Implementors of FooBar need to provide the method getFooBar() that returns an instance of a type which fullfills Foo as well as Bar.

What I tried so far is to do it with generics:

interface FooBar {
    <T extends Foo & Bar> T getFooBar()
}

class SomeImplementor implements FooBar {
    private FooAndBarImpl fSomeField;

    public <T extends Foo & Bar> T getFooBar() {
        return fSomeField;
    }

}

Given that FooAndBarImpl is some type provided by a framework or library and implements Foo and Bar this I think should work. However, it doesn't, because "FooAndBarImpl cannot be converted to T". Why is that? The contract implied by getFooBar() is not broken as I see it.

Another solution would be to define a new interface that extends Foo and Bar and to use that as return type. I just don't see much sense in returning a empty wrapper for the fSomeField in the getFooBar() implementation.

EDIT:

Would appreciate it if someone could explain why the generics approach doesn't work. I just don't see it.