Pipelines doesn't really give you an easy way to view the request output, but I can tell from this request there is still something wrong.
I recommend you go to https://requestbin.com/ or https://putsreq.com/ and create a bin/bucket. This is a temporary endpoint you can send to.
Then change your pipeline to point to that address and trigger it, this will let you see the actual raw request that is sent.
Then you can post it here for help, or drop it in a code editor or JSON Validator which will point out where the problem is. It's most likely syntax.
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Jeff Peterson
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