def object_to_http_body(model)
      return if model.nil?
      _body = nil
      if model.is_a?(Array)
        _body = model.map{|m| object_to_hash(m) }
      else
        _body = object_to_hash(model)
      end
      _body.to_json
    end
def object_to_http_body(model)
      return if model.nil?
      _body = nil
      if model.is_a?(Array)
        _body = model.map{|m| object_to_hash(m) }
      else
        _body = object_to_hash(model)
      end
      _body.to_json
    end
Convert object (array, hash, object, etc) to JSON string.
 @param [Object] model object to be converted into JSON string
 @return [String] JSON string representation of the object