Getting a "Bad Request" Error with API when Creating a Pull Request

#!bash
#!/usr/bin/env bash
set -o errexit
set -o xtrace

curl -X POST -H "Content-Type: application/json" \
 -u {username}:{password}\
 https://bitbucket.org/api/2.0/repositories/py-soft/sms_web/pullrequests \
 -d '{ "title": "Merge some branches", \
  "description": "stackoverflow example", \
  "source": { "branch": { "name": "TEST" }, \
  "destination": { "branch": { "name": "QA" } }, \
  "reviewers": [ { "username": "{username}" } ],\
   "close_source_branch": true }' > output.txt 2>&1

#!bash

  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed

  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0
  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0
  0     0    0     0    0     0      0      0 --:--:--  0:00:01 --:--:--     0
  0     0    0     0    0     0      0      0 --:--:--  0:00:02 --:--:--     0
100   267  100    11  100   256      3     87  0:00:03  0:00:02  0:00:01    87
Bad Request