DDMImpl.mergeFields throws NPE when upgrade from 6110

• Type: Bug
• Status: Closed
• Resolution: Fixed
• Affects Version/s: 6.2.10 EE GA1, 6.2.X EE
• Fix Version/s: 6.2.X EE
• Component/s: Dynamic Data Mapping > Upgrades
• Labels:
  • liferay-fixpack-portal-136-6210
  • liferay-fixpack-portal-164-6210
• Branch Version/s:
  6.2.x
• Backported to Branch:
  Committed
• Story Points: 1.25
• Fix Priority: 3
• Git Pull Request: https://github.com/brianchandotcom/liferay-portal-ee/pull/18593

Upgrade process fails with

2:10:48,697 INFO  [localhost-startStop-1][VerifyProcess:65] Verifying com.liferay.portal.verify.VerifyDynamicDataMapping
12:10:50,980 ERROR [localhost-startStop-1][DBUpgrader:247] Unable to execute verify process: com.liferay.portal.verify.VerifyException: com.liferay.portlet.dynamicdatamapping.StorageException: java.lang.NullPointerException
[...]
Caused by: java.lang.NullPointerException
	at com.liferay.portlet.dynamicdatamapping.util.DDMImpl.splitFieldsDisplayValue(DDMImpl.java:790)
	at com.liferay.portlet.dynamicdatamapping.util.DDMImpl.mergeFields(DDMImpl.java:369)
	at com.liferay.portlet.dynamicdatamapping.util.DDMUtil.mergeFields(DDMUtil.java:111)
	at com.liferay.portlet.dynamicdatamapping.storage.XMLStorageAdapter.doUpdate(XMLStorageAdapter.java:180)
	at com.liferay.portlet.dynamicdatamapping.storage.BaseStorageAdapter.update(BaseStorageAdapter.java:234)

Reproduction steps:
1. Start a clean 6.1.10 bundle
2. Go to Control Panel > Documents and media
3. Manage > Metadata sets > Add
3.1 Add a File upload field
3.2 Save
4. Manage > Document type > Add
4.1 Select Metadata Set > select the new metadata set
4.2 Save
5. Add a document with the new type and add a file to the metadata file upload field to.
6. Stop the portal
7. Upgrade to 6.2

reproducable only with

ee-6.2.x: 8d5976cd2957f96d112b0cb1d6e1299dd972e110 and earlier

Recent ee-6.2.x contains LPS-50549 which fails earlier when sanitizing HTML.
LPS-50549 was reverted.