title: On replacing JavaConversions with JavaConverters
body: <p>When I try to run code based on <a href="https://alvinalexander.com/scala/scala-java-system-environment-variables-properties" rel="noreferrer"><strong>this example</strong></a>, I get the following warning:</p>
  
  <pre><code>warning: object JavaConversions in package collection is deprecated (since 2.12.0): use JavaConverters
  </code></pre>
  
  <p>AFAICT, the lines responsible for the warning are these:</p>
  
  <pre><code>import scala.collection.JavaConversions._
  
  /* ... */
  
      for ((k,v) &lt;- environmentVars) println(s"key: $k, value: $v")
  </code></pre>
  
  <p>Replacing the <code>import</code> line with</p>
  
  <pre><code>import scala.collection.JavaConverters._
  </code></pre>
  
  <p>...is not enough; doing this alone results in the error:</p>
  
  <pre><code>error: value withFilter is not a member of java.util.Map[String,String]
      for ((k,v) &lt;- environmentVars) println(s"key: $k, value: $v")
  </code></pre>
  
  <p>What else must be done?</p>