title: Optional parametrization in Java with Generics
body: <p>Is is it possible to specify default type when parametrzing a class?
  Example:</p>
  
  <pre><code>// abstract class    
  public abstract class AbsClass&lt;T1 extends Par1Class, T2 extends Par2Class&gt; {
      // code 
  }
  
  // parametrized imlementation class
  public class RealClass extends AbsClass&lt;ClassThatExtendsPar1, ClassThatExtendsPar2Class&gt; {
     // code
  }
  
  // non-parametrized imlementation class
  public class RealClass extends AbsClass {
     // code
  }
  </code></pre>
  
  <p>in my implementation I have to specify NONE or ALL parameters. Is possible to make the second parameter non-mandatory, something like this:</p>
  
  <pre><code>// abstract class    
  public abstract class AbsClass&lt;T1 extends Par1Class, T2 extends Par2Class : default Par2Class &gt; {
      // code 
  }
  
  // parametrized only mandatory imlementation class
  public class RealClass extends AbsClass&lt;ClassThatExtendsPar1&gt; {
     // code
  }
  </code></pre>