Various Options API possibilities

Options.java

public class Options {
    public static void main(String[] args) {
        new Consumer1();
        new Consumer2();
        new Consumer3();
        new Consumer4();
        new Consumer5();
        new Consumer6();
        new Consumer7();
        new Consumer8();
    }
}

//
// 1. Old state
//

interface MetadataOptions1 {

}

class DefaultMetadataOptions1 implements MetadataOptions1 {

}

class Base1 {
    MetadataOptions1 getMetadataOptions() {
        return new DefaultMetadataOptions1();
    }
}

class Consumer1 extends Base1 {
    Consumer1() {
        getMetadataOptions();
        System.out.println("Consumer1: can't do an k/v stuff here");
    }
}

//
// 2. The current 5.3 state
//

interface MetadataOptions2 {

}

class FormatOptions2 {
    java.util.Properties properties = new java.util.Properties();
}

class DefaultMetadataOptions2 extends FormatOptions2 implements MetadataOptions2 {

}

class Base2 {
    MetadataOptions2 getMetadataOptions() {
        return new DefaultMetadataOptions2();
    }
}

class Consumer2 extends Base2 {
    Consumer2() {
        MetadataOptions2 opt = getMetadataOptions();
        if (opt instanceof FormatOptions2) {
            ((FormatOptions2) opt).properties.getProperty("foo", "bar");
        }
        System.out.println("Consumer2: can do k/v if it happens to be a format options");
    }
}

//
// 3. The CZI PR
//

interface MetadataOptions3 {

}

class FormatOptions3 {
    java.util.Properties properties = new java.util.Properties();
}

class DefaultMetadataOptions3 extends FormatOptions3 implements MetadataOptions3 {

}

class Base3 {
    MetadataOptions3 getMetadataOptions() {
        return new DefaultMetadataOptions3();
    }
}

class Consumer3 extends Base3 {
    Consumer3() {
        DefaultMetadataOptions3 ops = (DefaultMetadataOptions3) getMetadataOptions(); // Can't do any k/v here
        System.out.println("Consumer3: this is a bad assumption");
    }
}

//
// 4. Subclassing with deprecation
//

@Deprecated
interface MetadataOptions4 {

}

interface FormatOptions4 extends MetadataOptions4 {
    java.util.Properties getProperties();
}

class DefaultMetadataOptions4 implements FormatOptions4 {
    public java.util.Properties getProperties() {
        return new java.util.Properties();
    }
}

class Base4 {
    @Deprecated
    MetadataOptions4 getMetadataOptions() {
        return new DefaultMetadataOptions4();
    }
    FormatOptions4 getFormatOptions() {
        return new DefaultMetadataOptions4();
    }
}

class Consumer4 extends Base4 {
    Consumer4() {
        MetadataOptions4 mops = getMetadataOptions(); // Can't do any k/v here
        FormatOptions4 fops = getFormatOptions(); // Can do any k/v here
        System.out.println("Consumer4: use deprecation");
    }
}

//
// 5. Breaking interface addition
//

interface FormatOptions5 {
    java.util.Properties getProperties();
}

interface MetadataOptions5 extends FormatOptions5 {

}

class DefaultMetadataOptions5 implements MetadataOptions5 {
    public java.util.Properties getProperties() {
        return new java.util.Properties();
    }
}

class Base5 {
    MetadataOptions5 getMetadataOptions() {
        return new DefaultMetadataOptions5();
    }
}

class Consumer5 extends Base5 {
    Consumer5() {
        MetadataOptions5 mops = getMetadataOptions(); // Can do any k/v here
        System.out.println("Consumer5: use breaking");
    }
}

//
// 6. Use a subinterface return type
//

interface MetadataOptions6 {

}

interface FormatOptions6 extends MetadataOptions6 {
    java.util.Properties getProperties();
}


class DefaultMetadataOptions6 implements FormatOptions6 {
    public java.util.Properties getProperties() {
        return new java.util.Properties();
    }
}

class Base6 {
    FormatOptions6 getMetadataOptions() {
        return new DefaultMetadataOptions6();
    }
}

// Not working yet:
//class Other6 extends Base6 {
//    MetadataOptions6 getMetadataOptions() {
//        return new DefaultMetadataOptions6();
//    }
//}

class Consumer6 extends Base6 {
    Consumer6() {
        MetadataOptions6 mops = getMetadataOptions(); // Can't do any k/v here
        FormatOptions6 fops = getMetadataOptions(); // Can do any k/v here
        System.out.println("Consumer6: use a different return type");
    }
}

//
// 7. Use a new implementation
//

interface MetadataOptions7 {

}

class DynamicMetadataOptions7 implements MetadataOptions7 {
    public java.util.Properties getProperties() {
        return new java.util.Properties();
    }
}

class Base7 {
    MetadataOptions7 getMetadataOptions() {
        return new DynamicMetadataOptions7();
    }
}

class Other7 extends Base7 {
    MetadataOptions7 getMetadataOptions() {
        return new DynamicMetadataOptions7();
    }
}

class Consumer7 extends Base7 {
    Consumer7() {
        MetadataOptions7 mops = getMetadataOptions(); // Can't do any k/v here
        if (mops instanceof DynamicMetadataOptions7) {
            DynamicMetadataOptions7 fops = (DynamicMetadataOptions7) mops; // Can do any k/v here
        }
        System.out.println("Consumer7: use a different implementation");
    }
}

//
// 8. After 7, add methods to interface
//

interface MetadataOptions8 {
    java.util.Properties getProperties();
}

class DynamicMetadataOptions8 implements MetadataOptions8 {
    public java.util.Properties getProperties() {
        return new java.util.Properties();
    }
}

class Base8 {
    MetadataOptions8 getMetadataOptions() {
        return new DynamicMetadataOptions8();
    }
}

class Other8 extends Base8 {
    MetadataOptions8 getMetadataOptions() {
        return new DynamicMetadataOptions8();
    }
}

class Consumer8 extends Base8 {
    Consumer8() {
        MetadataOptions8 mops = getMetadataOptions(); // Can't do any k/v here
        if (mops instanceof DynamicMetadataOptions8) {
            DynamicMetadataOptions8 dops = (DynamicMetadataOptions8) mops; // Can do any k/v here
        }
        System.out.println("Consumer8: then add methods to interface");
    }
}