cloudwatch output plugin broke after 1.8 upgrade

[agnivade]

Relevant telegraf.conf:

[[outputs.cloudwatch]]
  region = "us-east-1"
  access_key = ""
  secret_key = ""
  namespace = "telegraf"

and some usual inputs -

[[inputs.nginx]]
  ## An array of Nginx stub_status URI to gather stats.
  urls = ["http://localhost:3000/status"]

  ## HTTP response timeout (default: 5s)
  response_timeout = "5s"

[[inputs.disk]]
  ## By default stats will be gathered for all mount points.
  ## Set mount_points will restrict the stats to only the specified mount points.
  # mount_points = ["/"]

  ## Ignore mount points by filesystem type.
  ignore_fs = ["tmpfs", "devtmpfs", "devfs", "overlay", "aufs", "squashfs"]

[[inputs.procstat]]
  exe = "backend"
  prefix = "backend"

System info:

Telegraf - 1.8.0-1
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=16.04
DISTRIB_CODENAME=xenial
DISTRIB_DESCRIPTION="Ubuntu 16.04.5 LTS"

Steps to reproduce:

1. Use the above config. Obviously fill in the access_key and secret_key
2. Run it using telegraf -config /etc/telegraf/telegraf.conf

Expected behavior:

No errors

Actual behavior:

2018-09-27T05:50:18Z E! CloudWatch: Unable to write to CloudWatch : InvalidParameter: 1 validation error(s) found.
- minimum field size of 1, PutMetricDataInput.MetricData[2].Dimensions[2].Value.
 
2018-09-27T05:50:18Z E! Error writing to output [cloudwatch]: InvalidParameter: 1 validation error(s) found.
- minimum field size of 1, PutMetricDataInput.MetricData[2].Dimensions[2].Value.

If I revert to 1.7.2-1, it works fine. Please advise.

[agnivade]

Thanks !