ServiceBuilder's convert-null property is ignored in CacheModel

• Type: Bug
• Status: Closed
• Resolution: Fixed
• Affects Version/s: 7.0.0 DXP FP45, 7.0.X, Master
• Fix Version/s: 7.0.0 DXP FP47, 7.0.0 DXP SP8, 7.0.X, 7.1.0 Beta 2, 7.1.X, 7.2.X, Master
• Component/s: Core Infrastructure > Service Builder
• Labels:
  • ee-ts
  • liferay-digital-enterprise-70-sp8
  • liferay-fixpack-de-47-7010
• Branch Version/s:
  7.2.x, 7.0.x
• Backported to Branch:
  Committed
• Story Points: 12
• Fix Priority: 2
• Git Pull Request: https://github.com/brianchandotcom/liferay-portal/pull/58946

In service.xml file String columns can be set to keep null value with specifying the convert-null="false" attribute.

This works unless the CacheModel is used, as explicit conversion to empty string (aka "") always happens for it in case of null value.

Steps to reproduce (DXP/7.0.x)

1. Deploy the attached bundles: convert.null.test.api-1.0.0.jar, convert.null.test.service-1.0.0.jar, convert.null.test.mvc.portlet-1.0.0.jar
2. Add ConvertNullTest-mvc portlet to a page and see what is logged:

   2018-04-20 13:35:31.223 INFO  [http-apr-8080-exec-10][ConvertNullTest:209] adding Foo...
   2018-04-20 13:35:31.234 INFO  [http-apr-8080-exec-10][ConvertNullTest:217] getting Foo...
   2018-04-20 13:35:31.234 INFO  [http-apr-8080-exec-10][ConvertNullTest:219] From DB: null
   2018-04-20 13:35:31.235 INFO  [http-apr-8080-exec-10][ConvertNullTest:226] getting Foo (this time from cache)...
   2018-04-20 13:35:31.235 INFO  [http-apr-8080-exec-10][ConvertNullTest:228] From Cache: "
   

The test bundles don't deploy on master.
As the issue is Service Builder related, there is no straightforward way to test the committed solution.