title: NIFI: NoClassDefFoundError - AbstractListProcessor
body: <p>I'm extending a standard processor to create a custom nifi processor. The project builds fine. But, when I restart my nifi after adding the newly generated nar to lib/ directory, nifi fails to start with <code>NoClassDefFoundError</code>:</p>
  <pre class="lang-java prettyprint-override"><code>    java.lang.NoClassDefFoundError: org/apache/nifi/processor/util/list/AbstractListProcessor
          at java.lang.ClassLoader.defineClass1(Native Method)
          at java.lang.ClassLoader.defineClass(ClassLoader.java:763)
          at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
          at java.net.URLClassLoader.defineClass(URLClassLoader.java:467)
          at java.net.URLClassLoader.access$100(URLClassLoader.java:73)
          at java.net.URLClassLoader$1.run(URLClassLoader.java:368)
          at java.net.URLClassLoader$1.run(URLClassLoader.java:362)
          at java.security.AccessController.doPrivileged(Native Method)
          at java.net.URLClassLoader.findClass(URLClassLoader.java:361)
          at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
          at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
          at java.lang.ClassLoader.defineClass1(Native Method)
          at java.lang.ClassLoader.defineClass(ClassLoader.java:763)
          at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
          at java.net.URLClassLoader.defineClass(URLClassLoader.java:467)
          at java.net.URLClassLoader.access$100(URLClassLoader.java:73)
          at java.net.URLClassLoader$1.run(URLClassLoader.java:368)
          at java.net.URLClassLoader$1.run(URLClassLoader.java:362)
          at java.security.AccessController.doPrivileged(Native Method)
          at java.net.URLClassLoader.findClass(URLClassLoader.java:361)
          at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
          at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
          at java.lang.Class.forName0(Native Method)
          at java.lang.Class.forName(Class.java:348)
          at java.util.ServiceLoader$LazyIterator.nextService(ServiceLoader.java:370)
          at java.util.ServiceLoader$LazyIterator.next(ServiceLoader.java:404)
          at java.util.ServiceLoader$1.next(ServiceLoader.java:480)
          at org.apache.nifi.nar.ExtensionManager.loadExtensions(ExtensionManager.java:138)
          at org.apache.nifi.nar.ExtensionManager.discoverExtensions(ExtensionManager.java:113)
          at org.apache.nifi.web.server.JettyServer.start(JettyServer.java:699)
          at org.apache.nifi.NiFi.&lt;init&gt;(NiFi.java:160)
          at org.apache.nifi.NiFi.main(NiFi.java:267)
  </code></pre>
  <p>Can someone help me understand if I'm missing something here.</p>
  <p>I'm using the following dependencies in processor-bundle's <code>POM.xml</code>:</p>
  <pre class="lang-xml prettyprint-override"><code>    &lt;dependency&gt;
          &lt;groupId&gt;org.apache.nifi&lt;/groupId&gt;
          &lt;artifactId&gt;nifi-api&lt;/artifactId&gt;
          &lt;version&gt;1.3.0&lt;/version&gt;
      &lt;/dependency&gt;
      &lt;dependency&gt;
          &lt;groupId&gt;org.apache.nifi&lt;/groupId&gt;
          &lt;artifactId&gt;nifi-standard-processors&lt;/artifactId&gt;
          &lt;version&gt;1.3.0&lt;/version&gt;
          &lt;scope&gt;provided&lt;/scope&gt;
      &lt;/dependency&gt;
      &lt;dependency&gt;
          &lt;groupId&gt;org.apache.nifi&lt;/groupId&gt;
          &lt;artifactId&gt;nifi-processor-utils&lt;/artifactId&gt;
          &lt;version&gt;1.3.0&lt;/version&gt;
      &lt;/dependency&gt;
      &lt;dependency&gt;
          &lt;groupId&gt;org.apache.nifi&lt;/groupId&gt;
          &lt;artifactId&gt;nifi-utils&lt;/artifactId&gt;
          &lt;version&gt;1.3.0&lt;/version&gt;
      &lt;/dependency&gt;
  </code></pre>
  <p>My imports in my code:</p>
  <pre class="lang-java prettyprint-override"><code>    import org.apache.commons.io.IOUtils;
      import org.apache.nifi.components.PropertyDescriptor;
      import org.apache.nifi.flowfile.attributes.CoreAttributes;
      import org.apache.nifi.processor.ProcessContext;
      import org.apache.nifi.processor.util.StandardValidators;
      import org.apache.nifi.processor.util.list.AbstractListProcessor;
      import org.apache.nifi.processors.standard.util.FileInfo;
      import org.apache.nifi.processors.standard.util.FileTransfer;
      import org.apache.nifi.processors.standard.ListFile;
  </code></pre>