Java Development Tools

I'm working with a class just like this:

abstract class TypeBase<X extends TypeBase<?>>{
	public abstract <Z extends Object> Z toJavaType();
}

This class models a type that could be equivalent to an existing java type.
Generic type Z allows subclasses to return appropriate java type thorugh toJavaType() method.

Few examples of implementations:

class MyIntType extends TypeBase<MyIntType>{
    int i;
    @Override
    public Integer toJavaType() {
        return new Integer(i);
    }
}
class MyDoubleType extends TypeBase<MyDoubleType>{
    double d;
    @Override
    public <Z> Z toJavaType() {
        return (Z)new Double(d);
    }
}

Problem comes here, both implementations generate warning.
The first:

Type safety: The return type Integer for toJavaType() from the type MyIntType needs unchecked conversion to  conform to Z from the type TypeBase<X>

The second:

Type safety: Unchecked cast from Double to Z

Any way to avoid these warnings without using @Suppress("unchecked") annotations?