Freemarker layout template that uses processPortlet method on TemplateProcessor prints errors on deployment

• Type: Regression Bug
• Status: Closed
• Resolution: Fixed
• Affects Version/s: 7.0.X, 7.1.X, Master
• Fix Version/s: 7.0.0 DXP FP60, 7.0.0 DXP SP9, 7.0.X, 7.1.10 DXP FP3, 7.1.1 CE GA2, 7.1.10.1 SP1, 7.1.X, Master
• Component/s: Liferay Themes
• Labels:
  • ee-ts
  • liferay-dxp-70-sp9
  • liferay-dxp-71-sp1
  • liferay-fixpack-de-60-7010
  • liferay-fixpack-dxp-3-7110
• Branch Version/s:
  7.1.x, 7.0.x
• Backported to Branch:
  Committed
• Story Points: 0.25
• Fix Priority: 4
• Git Pull Request: https://github.com/brianchandotcom/liferay-portal/pull/63525

Steps to Reproduce

1. Prepare a Liferay Tomcat bundle
2. Add the following to any layout template (.ftl) file in webapps/ROOT/layouttpl/custom

   ${processor.processPortlet("com_liferay_hello_world_web_portlet_HelloWorldPortlet")}

3. Start up Liferay

Expected behavior is that Liferay starts without errors. Actual behavior is that Liferay will error out on deploying the modified template, with an exception similar to the following:

The following has evaluated to null or missing:
==> processor.processPortlet  [in template "..." at line X, column Y]

Java stack trace (for programmers):
----
freemarker.core.InvalidReferenceException: [... Exception message was already printed; see it above ...]
	at freemarker.core.InvalidReferenceException.getInstance(InvalidReferenceException.java:131)
	at freemarker.core.UnexpectedTypeException.newDesciptionBuilder(UnexpectedTypeException.java:77)
	at freemarker.core.UnexpectedTypeException.<init>(UnexpectedTypeException.java:40)
	at freemarker.core.NonMethodException.<init>(NonMethodException.java:46)
	at freemarker.core.MethodCall._eval(MethodCall.java:84)
	at freemarker.core.Expression.eval(Expression.java:78)
	at freemarker.core.Expression.evalAndCoerceToString(Expression.java:82)
	at freemarker.core.DollarVariable.accept(DollarVariable.java:41)
	at freemarker.core.Environment.visit(Environment.java:324)
	at freemarker.core.MixedContent.accept(MixedContent.java:54)
	at freemarker.core.Environment.visit(Environment.java:324)
	at freemarker.core.Environment.process(Environment.java:302)
	at freemarker.template.Template.process(Template.java:325)
	at com.liferay.portal.template.freemarker.internal.FreeMarkerTemplate.processTemplate(FreeMarkerTemplate.java:123)
	at com.liferay.portal.template.AbstractSingleResourceTemplate.processTemplate(AbstractSingleResourceTemplate.java:78)
	at com.liferay.portal.service.impl.LayoutTemplateLocalServiceImpl._getColumns(LayoutTemplateLocalServiceImpl.java:515)