BS-14273 improve generation guidance

change the behavior of finish and add. When performFinish is false it
stay on the current page 

bundles/plugins/org.bonitasoft.studio.common/src/org/bonitasoft/studio/common/jface/dialog/FinishAndAddCustomWizardDialog.java

@@ -69,9 +69,10 @@ public abstract class FinishAndAddCustomWizardDialog extends CustomWizardDialog
     protected void buttonPressed(final int buttonId) {
         super.buttonPressed(buttonId);
         if (buttonId == CREATE_AND_NEW_ID) {
-            getWizard().performFinish();
-            close();
-            actionOnFinishAndAdd();
+            if (getWizard().performFinish()) {
+                close();
+                actionOnFinishAndAdd();
+            }
         }
     }