title: ScriptEngine with name "nashorn" is null
body: <p>I'm trying to create <code>ScriptEngine</code> with name <code>"nashorn"</code>:</p>
  
  <pre><code>ScriptEngineManager manager = new ScriptEngineManager();
  ScriptEngine engine = manager.getEngineByName("nashorn");
  if (engine == null) {
       System.out.println("engine == null");
  } 
  </code></pre>
  
  <p>But I always get </p>
  
  <pre><code>engine == null
  </code></pre>
  
  <p>Why is this happening? The docs say: </p>
  
  <blockquote>
    <p>The Nashorn engine is the default ECMAScript (JavaScript) engine
    bundled with the Java SE Development Kit (JDK).</p>
  </blockquote>
  
  <p>It means that the Nashorn engine is the default engine and must be present in JDK, don't it?</p>