Question

Would it make more sense making a utility method static or make non static with a scope of prototype?

i.e.

public static void setPdfVariables(String pdfFileName, boolean isDebugEnabled, ModelAndView modelAndView){
    modelAndView.addObject(PDF_FILE_NAME_KEY, pdfFileName);
    modelAndView.addObject(IS_DEBUG_ENABLED_KEY, isDebugEnabled);
}

Or
With a Scope of prototype

public void setPdfVariables(String pdfFileName, boolean isDebugEnabled, ModelAndView modelAndView){
    modelAndView.addObject(PDF_FILE_NAME_KEY, pdfFileName);
    modelAndView.addObject(IS_DEBUG_ENABLED_KEY, isDebugEnabled);
}

Answer 1

Seeing as you are only modifying the parameters you pass in to this method public static void seems fine.