title: Drools Rule depending on Knowledge from JDK Map (not within non-JDK Class)
body: <p>I'm trying to write the below Rule, which depends on Knowledge provided in the below <code>main</code> that uses just a JDK [library] Map (instead of a Map within a non-library Class).  But it doesn't seem to be working...</p>
  <p>Main method:</p>
  <pre><code>Map&lt;String, Float&gt; mapa = new HashMap&lt;String, Float&gt;();
  mapa.put(&quot;Height&quot;, (float)1.73);
  mapa.put(&quot;Weight&quot;, (float)79.0);
  mapa.put(&quot;BMI&quot;, mapa.get(&quot;Weight&quot;) /
                  (mapa.get(&quot;Height&quot;) * mapa.get(&quot;Height&quot;)));
  ksession.insert(mapa);
  </code></pre>
  <p>rule.drl:</p>
  <pre><code>rule &quot;Low BMI&quot;
      when
          $map : (Map(values(&quot;BMI&quot;)) &lt; 18.0)
      then 
          System.out.println(&quot;You have a low BMI&quot;);
  end
  </code></pre>
  <p>I want to compare the value of BMI inside of rule precondition, if this condition is true, so I want to show the message below.</p>
  <p>What is wrong?</p>