</Credentials>
    <AssumedUser>custom:Alice</AssumedUser>
  </AssumeRoleWithCustomTokenResult>
  <ResponseMetadata>
    <RequestId>16F26E081E36DE63</RequestId>
  </ResponseMetadata>
</AssumeRoleWithCustomTokenResponse>

username             (string)    MQTT username
password             (string)    MQTT password
qos                  (number)    set the quality of service priority, defaults to '0'
keep_alive_interval  (duration)  keep-alive interval for MQTT connections in s,m,h,d
reconnect_interval   (duration)  reconnect interval for MQTT connections in s,m,h,d
queue_dir            (path)      staging dir for undelivered messages e.g. '/home/events'