title: Intellij auto complete just not working for java.util.HashMap
body: <p>I'm using Intellij IDEA 2017.1.2 on MacOS High Sierra and the situation is when I type <code>OPTION+ENTER</code> it recommends me to import a class，Auto imports for all classes work well except for <code>HashMap</code>. For example, the class <code>HashTable</code> in the <code>java.util</code> package can auto complete.  </p>
  
  <p>I don't know what I had click or checked so how can I fix this problem? </p>