I have changed the methodo performFinish in class NewProcessDefinitionWizard like this:

public boolean performFinish() {
 try {
 IFolder folder = page.getProcessFolder();
 folder.create(true, true, null);

 IFile processDefinitionFile = folder.getFile("processdefinition.xml");
 processDefinitionFile.create(createInitialProcessDefinition(), true, null);

 IFile gpdFile = folder.getFile("gpd.xml");
 gpdFile.create(createInitialGpdInfo(), true, null);

 IFile abpmFile = folder.getFile("abpm.xml");
 abpmFile.create(createInitialABPMInfo(), true, null);

 IDE.openEditor(getActivePage(), gpdFile);
 openPropertiesView();
 BasicNewResourceWizard.selectAndReveal(gpdFile, getActiveWorkbenchWindow());
 return true;
 } catch (CoreException e) {
 e.printStackTrace();
 return false;
 }
 }

private ByteArrayInputStream createInitialABPMInfo() {
 String parName = page.getProcessFolder().getName();
 String processName = parName;

 StringBuffer buffer = new StringBuffer();
 buffer.append("<?xml version=\"1.0\" encoding=\"UTF-8\"?>");
 buffer.append("\n");
 buffer.append("\n");
 buffer.append("<process-definition\n" +
 " name=\"" + processName + "\">\n" +
 "</process-definition>");
 return new ByteArrayInputStream(buffer.toString().getBytes());
 }

When I debug, no errors occours, but when I exported the project org.jbpm.gd.jpdl.ui like a jar and put the jar in eclipse plugin folder and, after that, I start the eclipse and try to create a new JBPM Project Process, I got the error: Plug-in org.jbpm.gd.jpdl.ui was unable to load class org.jbpm.ui.wizard.NewProcessDefinitionWizard