def validate_required_params!(params, *required)
      required.flatten.each do |param|
        if !params.key?(param) || params[param].to_s.empty?
          raise ArgumentError, "Missing required parameter: #{param}."
        end
      end
    end
def validate_required_params!(params, *required)
      required.flatten.each do |param|
        if !params.key?(param) || params[param].to_s.empty?
          raise ArgumentError, "Missing required parameter: #{param}."
        end
      end
    end
Validate required parameters.