title: Assert key in hashmap JUnit
body: <p>I thought it was going to be easy but can anyone tell me how I can test HashMap to see if it has some value in JUnit?</p>
  
  <pre><code>assertThat(myMap, ??);
  </code></pre>
  
  <p>I tried something like:</p>
  
  <pre><code>assertThat(myMap, hasEntry("Key", notNullValue()));
  </code></pre>
  
  <p>...But I couldn't make it compile since my import to hasEntry and notNullValue() is correct.
  Does anyone know what the correct import pkg for them should be?</p>