IllegalStateException: response.getOutputStream() called after response.getWriter() while attempting navigation
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I have created a custom form in my custom Confluence plugin called Freeway.

My question has lot of code snippets so i am using pastebin for code. Please bear with me :)

This is the page how it looks like http://imageshack.us/f/109/newpagec.png/. I added my custom 'Freeway Project Creation' tab. The atlassian-plugin.xml looks like this
http://pastebin.com/j9Da4k1i

This is the class mentioned inside the plugin.xml http://pastebin.com/NV6LXXu2 and this is called as a result of the clicking on the newly created tab.
Now as seen in the image ; my page has a form and a button. So on filling it up,i have configured a doEdit method in my class named FreewayProjectActionSend which is this.
http://pastebin.com/Jta2WxKg.

The VM for the UI seen in the image is this http://pastebin.com/pGeFieNV.
I have got the getters and setters configured for the four input values of project name, po reference, customer reference  and special instructions. On the click of the submit, the 
doEdit method mentioned earlier does get fired; (since i see the System.out.println values on the console.)

How ever the navigation to the next page does not work inspite of the 'success' configured in my action to 'successPage.vm'.
The placeholder successpage is this http://pastebin.com/XrSBWyXe .

The problem i am facing is that:

Clicking on the submit on the form of my page seen in the UI screenshot results in this error http://pastebin.com/DFubwybV  due to response.getOutputStream() called after response.getWriter()

Could you please help me out.
