title: Error PayPal plugin on grails 2.0.0.RC3
body: <p>I use grails 2.0.0.rc3, when I install PayPal plugin I have this error:</p>
  
  <pre><code>Error Compilation error: startup failed:
  /Users/sartre/.grails/2.0.0.M1/projects/testapp/plugins/paypal-0.6.4/grails-app/controllers/org/grails/paypal/PaypalController.groovy: -1: The return type of java.lang.Object notify() in org.grails.paypal.PaypalController is incompatible with void notify() in java.lang.Object
  . At [-1:-1] @ line -1, column -1.
  1 error
  </code></pre>
  
  <p>How can I fix it?</p>
  
  <p>Many thanks for any idea</p>