code: private void _buildNullBinding(
                      final NullBinding binding,
                      final StringBuilder stmt
                      )
      {
          String  property = binding.getProperty();
  
          if (binding.isNotNull()) {
              stmt.append( " is_defined(" );
          } else {
              stmt.append( " is_undefined(" );
          }
  
          _buildProperty( property, stmt );
          //throws SearchException
  
          stmt.append( ")" );
      }
docs: NullBinding
  is_undefiend(T.p)
  is_defnied(T.p)