title: Eclipse complains about "No grammar constraint (DTD or XML Schema) referenced in the document" despite one being specified
body: <p>We are building a WAR file to be deployed on an IBM websphere server. We created our configuration files according to the websphere samples:</p>
  
  <p><em>ibm-wb-bnd.xml</em></p>
  
  <pre><code>&lt;?xml version="1.0" encoding="UTF-8"?&gt;
  &lt;web-bnd xmlns="http://websphere.ibm.com/xml/ns/javaee"
           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
           xsi:schemaLocation="http://websphere.ibm.com/xml/ns/javaee http://websphere.ibm.com/xml/ns/javaee/ibm-web-bnd_1_1.xsd"
           version="1.0"&gt;
  
      &lt;!-- snipped settings --&gt;
  &lt;/web-bnd&gt;
  </code></pre>
  
  <p><em>ibm-web-ext.xml</em></p>
  
  <pre><code>&lt;?xml version="1.0" encoding="UTF-8"?&gt;
  &lt;web-ext xmlns="http://websphere.ibm.com/xml/ns/javaee"
           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
           xsi:schemaLocation="http://websphere.ibm.com/xml/ns/javaee http://websphere.ibm.com/xml/ns/javaee/ibm-web-ext_1_0.xsd"
           version="1.0"&gt;
  
      &lt;!-- snipped settings --&gt;
  &lt;/web-ext&gt;
  </code></pre>
  
  <p>This works and the deployed WAR file works. However, in eclipse we get a warning telling us the "No grammar constraints (DTD or XML Schema) referenced in the document."</p>
  
  <p>I would have expected this without the schema parameters, but since we included that, I'm wondering what the reason for this warning is. Does it have to do with the fact that the URL websphere.ibm.com does not seem to exist? Why would the IBM samples contain these addresses then? Can I supply the schema files differently?</p>