title: Adding new java based PMD rule in eclipse pmd plugin
body: <p>How can we add a new java based pmd rule in eclipse pmd plugin?</p>
  
  <p>I am getting following error:</p>
  
  <p><strong>Invalid Class implementation.The class must be in plugin classpath and implement the rule interface.</strong> </p>
  
  <p>I have extended rule class with AbstractRule class. </p>