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public class Main {
 
    interface Foo { }
 
    interface Bar { }
 
    static class FooBarImpl implements Foo, Bar { }
 
    //a simple container class
    static class FooBarContainer<T extends Foo & Bar> {
 
        private final T fooBar;
 
        public FooBarContainer(T fooBar) {
            this.fooBar = fooBar;
        }
 
        public T get() {
            return fooBar;
        }
 
        //a silly static unwrap method
        static <T extends Foo & Bar> T unwrap(FooBarContainer<T> fooBarContainer) {
            return fooBarContainer.get();
        }
    }
 
    public static void main(String[] args) {
 
        // concrete parameterized type
        FooBarContainer<FooBarImpl> fooBarContainer = new FooBarContainer<FooBarImpl>(new FooBarImpl());
        // wildcard parameterized type
        FooBarContainer<?> unknownFooBarContainer = fooBarContainer;
 
        // passing in a concrete parameterized type
        FooBarContainer.<FooBarImpl>unwrap(fooBarContainer); // T is specified to be FooBarImpl
        FooBarContainer.unwrap(fooBarContainer);             // T is inferred to be FooBarImpl
 
        // passing in a wildcard parameterized type
        FooBarContainer.<?>unwrap(unknownFooBarContainer);   // T is specified to be ? - compiler error
        FooBarContainer.unwrap(unknownFooBarContainer);      // T is inferred to be ? - legal (!)
 
        // unwrapping unknownFooBarContainer returns a reference of type ? extends Foo & Bar
        // we can assign to Foo or Bar, but not both
        Foo foo = FooBarContainer.unwrap(unknownFooBarContainer);
        Bar bar = FooBarContainer.unwrap(unknownFooBarContainer);
 
        // if unwrap were expensive, we would be forced to cast
        Foo foo2 = FooBarContainer.unwrap(unknownFooBarContainer);
        Bar bar2 = (Bar)foo2;
 
        // so this is where the hypothetical syntax would come in handy
        Foo&Bar fooBar = FooBarContainer.unwrap(unknownFooBarContainer);
    }
}

Main.java:40: error: illegal start of type
        FooBarContainer.<?>unwrap(unknownFooBarContainer);   // T is specified to be ? - compiler error
                         ^
Main.java:40: error: <identifier> expected
        FooBarContainer.<?>unwrap(unknownFooBarContainer);   // T is specified to be ? - compiler error
                          ^
Main.java:40: error: illegal start of expression
        FooBarContainer.<?>unwrap(unknownFooBarContainer);   // T is specified to be ? - compiler error
                           ^
Main.java:40: error: illegal start of expression
        FooBarContainer.<?>unwrap(unknownFooBarContainer);   // T is specified to be ? - compiler error
                                 ^
Main.java:40: error: ';' expected
        FooBarContainer.<?>unwrap(unknownFooBarContainer);   // T is specified to be ? - compiler error
                                                        ^
Main.java:53: error: not a statement
        Foo&Bar fooBar = FooBarContainer.unwrap(unknownFooBarContainer);
           ^
Main.java:53: error: ';' expected
        Foo&Bar fooBar = FooBarContainer.unwrap(unknownFooBarContainer);
               ^
7 errors

Standard output is empty