def content_type=(new_val)
      return nil if new_val == @content_type
      raise JSS::InvalidDataError, "content_type must be one of :#{CONTENT_TYPES.keys.join ', :'}" unless \
        CONTENT_TYPES.keys.include? new_val
      @content_type = new_val
      @need_to_update = true
    end
def content_type=(new_val)
      return nil if new_val == @content_type
      raise JSS::InvalidDataError, "content_type must be one of :#{CONTENT_TYPES.keys.join ', :'}" unless \
        CONTENT_TYPES.keys.include? new_val
      @content_type = new_val
      @need_to_update = true
    end
Set the content_type sent to the url
 Must be one of the keys of CONTENT_TYPES, i.e. :xml or :json

 @param new_val[Symbol] The new content_type

 @return [void]