FreeMarker template error occurs when the template contains Site ID variable

• Type: Regression Bug
• Status: Closed
• Resolution: Fixed
• Affects Version/s: Master
• Fix Version/s: 7.4.0 CE GA1, 7.4.13 DXP GA1, Master
• Component/s: Content Display Widgets > Web Content Display widget, Out of the box Fragments > Content Display Fragment
• Labels:
  • QA-AUTOMATION
• Fix Priority: 4
• Last Working Version:
  Master
• Git Pull Request: https://github.com/liferay-echo/liferay-portal/pull/3868
• QA Test Name:
  • LocalFile.ContentPagesWithContributedFragments#SelectCustomWebContentTemplateInContentDisplay
  • LocalFile.StagingUsecase#ImportLARsOnStagedSite
• QA Test Score: 10

Step to reproduce:

1. Add a web content based on Basic Web Content
2. Add a new template for Basic Web Content
3. Select Site ID variable and Content field
4. Type name > Save
5. Add a page based on Blank
6. Add a Content Display fragment to page
7. Select the web content in Content Display
8. Select the new template in Template field

Expected Results:
The groupId and content of web content should be shown in Content Display.

Actual Results:
The following freemarker template error occurs.

2021-03-01 03:07:23.971 ERROR [http-nio-8080-exec-7][runtime:59] Error executing FreeMarker template
FreeMarker template error:
The following has evaluated to null or missing:
==> groupId  [in template "20100#20126#null" at line 1, column 3]

----
Tip: If the failing expression is known to legally refer to something that's sometimes null or missing, either specify a default value like myOptionalVar!myDefault, or use <#if myOptionalVar??>when-present<#else>when-missing</#if>. (These only cover the last step of the expression; to cover the whole expression, use parenthesis: (myOptionalVar.foo)!myDefault, (myOptionalVar.foo)??
----

----
FTL stack trace ("~" means nesting-related):
        - Failed at: ${groupId}  [in template "20100#20126#null" at line 1, column 1]
----

Java stack trace (for programmers):
----
freemarker.core.InvalidReferenceException: [... Exception message was already printed; see it above ...]
        at freemarker.core.InvalidReferenceException.getInstance(InvalidReferenceException.java:134)
        at freemarker.core.EvalUtil.coerceModelToTextualCommon(EvalUtil.java:479)
        at freemarker.core.EvalUtil.coerceModelToStringOrMarkup(EvalUtil.java:401)
        at freemarker.core.EvalUtil.coerceModelToStringOrMarkup(EvalUtil.java:370)
        at freemarker.core.DollarVariable.calculateInterpolatedStringOrMarkup(DollarVariable.java:100)
        at freemarker.core.DollarVariable.accept(DollarVariable.java:63)
        at freemarker.core.Environment.visit(Environment.java:331)
        at freemarker.core.Environment.visit(Environment.java:337)
        at freemarker.core.Environment.process(Environment.java:310)
        at freemarker.template.Template.process(Template.java:383)

Reproduced on:
Tomcat 9.0.40 + MySQL 5.7. Portal master GIT ID: b82ae9277239522445506e58e59a2fedf8bce42d.