 to change content type and character encoding. This method has no effect if
 called after the response has been committed. It does not set the response's character encoding if it is called after
 <code>getWriter</code> has been called or after the response has been committed.
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 If calling this method has an effect (as per the previous paragraph), calling this method with <code>null</code> clears
 any content type set via a previous call to this method and clears any character encoding set via a previou