title: Where is the declaration of JUnit Matcher#startsWith?
body: <p>I was browsing the <a href="http://kentbeck.github.com/junit/javadoc/latest/org/junit/rules/ExpectedException.html" rel="noreferrer">junit <code>ExpectedExceptions</code>' javadoc</a> and I can't understand where the <code>startsWith</code> in their example comes from (marked HERE in the code). I checked the <a href="http://kentbeck.github.com/junit/javadoc/latest/org/hamcrest/CoreMatchers.html" rel="noreferrer"><code>CoreMatcher</code> utility class</a> but could not find any static <code>startsWith</code> method.</p>
  
  <p>Where is that method located?</p>
  
  <p>(I can obviously write it myself but that's not the point)</p>
  
  <pre><code>public static class HasExpectedException {
      @Rule
      public ExpectedException thrown = ExpectedException.none();
  
      @Test
      public void throwsNullPointerExceptionWithMessage() {
          thrown.expect(NullPointerException.class);
          thrown.expectMessage("happened?");
          thrown.expectMessage(startsWith("What")); //HERE
          throw new NullPointerException("What happened?");
      }
  }
  </code></pre>