title: How do you convert a java.util.Collections.unmodifiableMap to an immutable Scala Map?
body: <p>I'm trying to convert the parameter map from a ServletRequest to a Scala Map in Scala 2.9.0.1:</p>
  
  <pre><code>val params = request.getParameterMap.asInstanceOf[Map[String, Array[String]]]
  </code></pre>
  
  <p>I've imported collection.JavaConversions._, and at runtime this is thrown:</p>
  
  <pre><code>java.lang.ClassCastException: java.util.Collections$UnmodifiableMap cannot be cast to scala.collection.immutable.Map
  </code></pre>