title: Why am I getting errors in jdoconfig.xml?
body: <p>Eclipse marker tab shows some <code>xml</code> problem. This occurred when I checked <code>dynamic web module</code> in the <code>Project Facets</code>. </p>
  
  <p>This is my project hierarchy :</p>
  
  <p><img src="https://i.stack.imgur.com/ai2o7.png" alt="enter image description here">  </p>
  
  <p><code>jdconfig.xml</code> (automatically generated) :</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;jdoconfig xmlns="http://java.sun.com/xml/ns/jdo/jdoconfig"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:noNamespaceSchemaLocation="http://java.sun.com/xml/ns/jdo/jdoconfig"&gt;
  
     &lt;persistence-manager-factory name="transactions-optional"&gt;
         &lt;property name="javax.jdo.PersistenceManagerFactoryClass"
         value="org.datanucleus.api.jdo.JDOPersistenceManagerFactory"/&gt;
         &lt;property name="javax.jdo.option.ConnectionURL" value="appengine"/&gt;
         &lt;property name="javax.jdo.option.NontransactionalRead" value="true"/&gt;
         &lt;property name="javax.jdo.option.NontransactionalWrite" value="true"/&gt;
         &lt;property name="javax.jdo.option.RetainValues" value="true"/&gt;
         &lt;property name="datanucleus.appengine.autoCreateDatastoreTxns" value="true"/&gt;
         &lt;property name="datanucleus.appengine.singletonPMFForName" value="true"/&gt;
     &lt;/persistence-manager-factory&gt;
  &lt;/jdoconfig&gt;
  </code></pre>
  
  <p>Errors shown in the marker window :</p>
  
  <pre><code>cvc-elt.1: Cannot find the declaration of element 'jdoconfig'.
  </code></pre>
  
  <p>What is the reason I am getting this error ? </p>
  
  <p>Also,what is <code>jdoconfig.xml</code> ?</p>