title: getResource return null url in context of module
body: <p>I am new to Java Modularity. I am using Java 9.</p>
  
  <p>The program compiles without complaint. It also runs perfectly well from the "exploded module" folder, but with one exception: it throws an exception whose cause originates with the following line of code:</p>
  
  <pre><code>URL introURL = AboutPanel.class.getResource("help.html");
  </code></pre>
  
  <p><code>introURL</code> is being assigned null. </p>
  
  <p>When running the program in Eclipse, or from a jar file exported from Eclipse, the URL is populated correctly with the address of a resource file (help.html) that is in the same directory as the calling class.</p>
  
  <p>Here is the command I use to run the program from the "exploded module" that is in the "out" folder:</p>
  
  <pre><code>java -p out/ -m moduleTCD/com.adonax.tanpura.TCDLaunch  
  </code></pre>
  
  <p>The project consists of two packages that I am bundling together in a single module.</p>
  
  <pre><code>src/moduleTCD/com/adonax/tanpura
                          /pfaudio
  </code></pre>
  
  <p>The "main" class (entry point) is <code>tanpura.TCDLaunch</code>.</p>
  
  <p>Here is the <code>module-info.java</code> class contents:</p>
  
  <pre><code>module moduleTCD {
      exports com.adonax.tanpura;
  
      requires java.base;
      requires java.desktop;
  }
  </code></pre>
  
  <p>The error statement, when trying to run from the command line:</p>
  
  <pre><code>java.io.IOException: invalid url
      at java.desktop/javax.swing.JEditorPane.setPage(Unknown Source)
      at moduleTCD/com.adonax.tanpura.documentation.AboutPanel.&lt;init&gt;(AboutPanel.java:28)
      at moduleTCD/com.adonax.tanpura.panels.ControlPanel.initializeHelpPanel(ControlPanel.java:525)
      at moduleTCD/com.adonax.tanpura.panels.ControlPanel.&lt;init&gt;(ControlPanel.java:163)
      at moduleTCD/com.adonax.tanpura.TCDLaunch.main(TCDLaunch.java:43)
  </code></pre>
  
  <p>This exception is thrown in a try/catch for IOException at the point where the JEditorPane method setPage is called with null as an argument.</p>
  
  <pre><code>textArea.setPage(introURL);
  </code></pre>
  
  <p>At first, I didn't have an exports line in my module-info.java, but added it when I read the following from the API for <code>Class.getResource</code>:</p>
  
  <blockquote>
    <p>Returns:
        A URL object; null if no resource with this name is found, the resource cannot be located by a URL, the resource is in a package that
    is not open to at least the caller module, or access to the resource
    is denied by the security manager.</p>
  </blockquote>
  
  <p>This raised the possibility that the package might be needed by <code>Class</code> in the module Java.base. The <code>exports</code> command there now is the broadest possible. But adding it did not change the error. I'm wondering if there is something wrong with how I did this, or if there is something else I am overlooking.</p>