code: @Override
      public <N extends Number> Expression<N> diff(Expression<? extends N> arg0, Expression<? extends N> arg1)
      {
          // TODO Auto-generated method stub
          return null;
      }
docs: /*
  (non-Javadoc)
  
  @see
  javax.persistence.criteria.CriteriaBuilder#diff(javax.persistence.criteria
  .Expression, javax.persistence.criteria.Expression)