Example of generic delegation

Main.java

public class Main {

    public static void main(String[] args) {
        Structure<Alpha, Alpha1, Alpha2> first = new First(new Alpha());
        Structure<Beta, Beta1, Beta2> second = new Second(new Beta());
        Structure<Object, Object, Object> template = new Template();

        first.getValue().setValue(first.getValue().getValue());
        //first.getValue().setValue(second.getValue().getValue());
        //first.getValue().setValue(template.getValue().getValue());

        //second.getValue().setValue(first.getValue().getValue());
        second.getValue().setValue(second.getValue().getValue());
        //second.getValue().setValue(template.getValue().getValue());

        template.getValue().setValue(first.getValue().getValue());
        template.getValue().setValue(second.getValue().getValue());
        template.getValue().setValue(template.getValue().getValue());
    }

    interface Structure<SELF, DELEGATE, NESTED> {
        Structure1<DELEGATE, NESTED> getValue();
        void setValue(Structure1<? extends DELEGATE, ? extends NESTED> value);
    }

    interface Structure1<SELF, DELEGATE> {
        Structure2<? extends DELEGATE> getValue();
        void setValue(Structure2<? extends DELEGATE> value);
    }

    interface Structure2<SELF> {
        String getValue();
        void setValue(String value);
    }

    static class Alpha {
        private Alpha1 value = new Alpha1();
        public Alpha1 getValue() { return value; }
        public void setValue(Alpha1 value) { this.value = value; }
    }

    static class Alpha1 {
        private Alpha2 value = new Alpha2();
        public Alpha2 getValue() { return value; }
        public void setValue(Alpha2 value) { this.value = value; }
    }

    static class Alpha2 {
        private String value = "foo";
        public String getValue() { return value; }
        public void setValue(String value) { this.value = value; }
    }

    static class Beta {
        private Beta1 value = new Beta1();
        public Beta1 getValue() { return value; }
        public void setValue(Beta1 value) { this.value = value; }
    }

    static class Beta1 {
        private Beta2 value = new Beta2();
        public Beta2 getValue() { return value; }
        public void setValue(Beta2 value) { this.value = value; }
    }

    static class Beta2 {
        private String value = "bar";
        public String getValue() { return value; }
        public void setValue(String value) { this.value = value; }
    }

    static class First implements Structure<Alpha, Alpha1, Alpha2> {
        final Alpha delegate;
        public First(Alpha delegate) { this.delegate = delegate; }
        @Override public Structure1<Alpha1, Alpha2> getValue() { return new First1(delegate.getValue()); }
        @Override public void setValue(Structure1<? extends Alpha1, ? extends Alpha2> value) { delegate.setValue(((First1) value).delegate); }
    }

    static class First1 implements Structure1<Alpha1, Alpha2> {
        final Alpha1 delegate;
        public First1(Alpha1 delegate) { this.delegate = delegate; }
        @Override public Structure2<Alpha2> getValue() { return new First2(delegate.getValue()); }
        @Override public void setValue(Structure2<? extends Alpha2> value) { delegate.setValue(((First2) value).delegate); }
    }

    static class First2 implements Structure2<Alpha2> {
        final Alpha2 delegate;
        public First2(Alpha2 delegate) { this.delegate = delegate; }
        @Override public String getValue() { return delegate.getValue(); }
        @Override public void setValue(String value) { delegate.setValue(value); }
    }

    static class Second implements Structure<Beta, Beta1, Beta2> {
        final Beta delegate;
        public Second(Beta delegate) { this.delegate = delegate; }
        @Override public Structure1<Beta1, Beta2> getValue() { return new Second1(delegate.getValue()); }
        @Override public void setValue(Structure1<? extends Beta1, ? extends Beta2> value) { delegate.setValue(((Second1) value).delegate); }
    }

    static class Second1 implements Structure1<Beta1, Beta2> {
        final Beta1 delegate;
        public Second1(Beta1 delegate) { this.delegate = delegate; }
        @Override public Structure2<Beta2> getValue() { return new Second2(delegate.getValue()); }
        @Override public void setValue(Structure2<? extends Beta2> value) { delegate.setValue(((Second2) value).delegate); }
    }

    static class Second2 implements Structure2<Beta2> {
        final Beta2 delegate;
        public Second2(Beta2 delegate) { this.delegate = delegate; }
        @Override public String getValue() { return delegate.getValue(); }
        @Override public void setValue(String value) { delegate.setValue(value); }
    }

    static class Template implements Structure<Object, Object, Object> {
        private Structure1<?, ?> value = new Template1();
        @Override @SuppressWarnings("unchecked") public Structure1<Object, Object> getValue() { return (Structure1<Object, Object>) value; }
        @Override public void setValue(Structure1<?, ?> value) { this.value = value; }
    }

    static class Template1 implements Structure1<Object, Object> {
        private Structure2<?> value = new Template2();
        @Override @SuppressWarnings("unchecked") public Structure2<Object> getValue() { return (Structure2<Object>) value; }
        @Override public void setValue(Structure2<?> value) { this.value = value; }
    }

    static class Template2 implements Structure2<Object> {
        private String value = "qux";
        @Override public String getValue() { return value; }
        @Override public void setValue(String value) { this.value = value; }
    }
}