title: How to handle map result(two column results) using mybatis interface not sqlSession
body: <p>I use Spring boot and Mybatis(interface and mapper.xml) in java web app. </p>
  
  <p>My purpose is to convert result list that contains two columns 'name' and 'count' to a map. The first column should be used as a key and the second column as a value in that map. </p>
  
  <p>I know I should rewrite ResultHandler, while how could it take effect by using interface?</p>