title: java web start fails to locate java runtime
body: <p>Hi I am trying to run javaws but it prompts:
  To open this Web Start application you need to download the Java Runtime Environment.</p>
  
  <p>I am sure JRE is installed, maybe javaws does not find it, how do I fix that?</p>
  
  <pre><code>Johns-MacBook-Pro:~ johnmactavish$ java --version
  java 13.0.2 2020-01-14
  Java(TM) SE Runtime Environment (build 13.0.2+8)
  Java HotSpot(TM) 64-Bit Server VM (build 13.0.2+8, mixed mode, sharing)
  Johns-MacBook-Pro:~ johnmactavish$ javaws
  No Java runtime present, requesting install.
  Unable to locate a Java Runtime to invoke.
  Johns-MacBook-Pro:~ johnmactavish$ 
  </code></pre>