Cannot update DDL record via /ddlrecord/update-record jsonws method

• Type: Bug
• Status: Closed
• Resolution: Fixed
• Affects Version/s: 6.2.10 EE GA1, 6.2.X EE, 7.0.0 CE GA1, 7.0.0 DXP SP1, Master
• Fix Version/s: 6.2.X EE, 7.0.0 DXP FP1, 7.0.2 CE GA3, 7.0.3 CE GA4, 7.1.X, Master
• Component/s: Dynamic Data Lists, Web Services, Web Services > JSON WS
• Labels:
  • QA-AUTOMATION
  • backend_test
  • fw_test_integration
  • liferay-digital-enterprise-70-sp1
  • liferay-fixpack-de-1-7010
  • liferay-fixpack-portal-122-6210
• Branch Version/s:
  6.2.x
• Backported to Branch:
  Committed
• Git Pull Request: https://github.com/brianchandotcom/liferay-portal/pull/41511

Description:
When updating a pre-existing DDL record via /ddlrecord/update-record method, the servers returns "java.lang.NullPointerException."

Steps to reproduce
1. Create a Data Definition in Site Admin > Dynamic Data Lists > Data Definitions with a single text field, change name of field to "text"
2. Add a list using this Data Definition
3. Add a record in the newly created list, copy recordId (can be found in edit record markup)
4. Navigate to /api/jsonws?signature=%2Fddlrecord%2Fupdate-record-5-recordId-displayIndex-fieldsMap-mergeFields-serviceContext
5. Set recordId to recordId copied from step 3, set displayIndex to 0, set fieldsMap to

{"text": "new value"}

, set mergeFields to true
6. Click invoke
7. Assert error message
Expected Behavior: Result shows the column values for the record
Actual Behavior: Result shows NPE is thrown

Testing:
Reproduced in 6.2.x - ea8d034b9afdc6b4b76dde47ac12f1eaa6ba65d6
Reproduced in master - 3eb7e539ef0bd99e81542dd55a5f45331b5bb650

Note: the url for master (and 7.0) is /api/jsonws?contextName=ddl&signature=%2Fddl.ddlrecord%2Fupdate-record-5-recordId-displayIndex-fieldsMap-mergeFields-serviceContext#serviceResults