def http_queue_start
      env = environment
      return unless env
      env_var = env["HTTP_X_QUEUE_START".freeze] || env["HTTP_X_REQUEST_START".freeze]
      return unless env_var
      cleaned_value = env_var.tr("^0-9".freeze, "".freeze)
      return if cleaned_value.empty?

      value = cleaned_value.to_i
      if value > 4_102_441_200_000
        # Value is in microseconds. Transform to milliseconds.
        value / 1_000
      elsif value < 946_681_200_000
        # Value is too low to be plausible
        nil
      else
        # Value is in milliseconds
        value
      end
    end
def http_queue_start
      env = environment
      return unless env
      env_var = env["HTTP_X_QUEUE_START".freeze] || env["HTTP_X_REQUEST_START".freeze]
      return unless env_var
      cleaned_value = env_var.tr("^0-9".freeze, "".freeze)
      return if cleaned_value.empty?

      value = cleaned_value.to_i
      if value > 4_102_441_200_000
        # Value is in microseconds. Transform to milliseconds.
        value / 1_000
      elsif value < 946_681_200_000
        # Value is too low to be plausible
        nil
      else
        # Value is in milliseconds
        value
      end
    end
Returns HTTP queue start time in milliseconds.

 @return [nil] if no queue start time is found.
 @return [nil] if begin time is too low to be plausible.
 @return [Integer] queue start in milliseconds.