Set only allows string when it comes to body.service

[jkaufman-LogRhythm]

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For confirmed bugs, please report:

• Version: 7
• Operating System: Centos 7
• Discuss Forum URL: https://discuss.elastic.co/t/header-transform-concern-need-help/269064/14
• Steps to Reproduce:

request.transforms:
    - set:
       target: body.service
       value: ["directory"]

The work around was to use append for each string (example):
- append:
target: body.service
value: "value1"
- append:
target: body.service
value: "value2"

Sadly the api I am using only allows one string in an array, so still I would require a way to put an array in the set value.

[botelastic]

This issue doesn't have a Team:<team> label.