Unable to use variable for docker port mapping

Issue Summary

Fail to use Bamboo variable for Docker Task port mapping

Steps to Reproduce

1. Create a variable "port"
2. Fill in "${bamboo.port}" into Docker task Port Mapping

Expected Results

Able to be added

Actual Results

It fail with message "Invalid port"

Notes

• Docker task Port Mapping only accept number.
• Related to https://jira.atlassian.com/browse/BAM-17188

Workaround

Use Script task to run docker command so that it can use Bamboo Variable