FreeMarker template error (HTML_DEBUG mode; use RETHROW in production!)

For "...(...)" callee: Expected a method or function, but this has evaluated to a string (wrapper: f.t.SimpleScalar):
==> Catalog.createTime?string  [in template "xcl_pc/template/detail.template.html" at line 22, column 33]

----
FTL stack trace ("~" means nesting-related):
	- Failed at: ${Catalog.createTime?string("yyyy-MM-...  [in template "xcl_pc/template/detail.template.html" at line 22, column 31]
----

Java stack trace (for programmers):
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freemarker.core.NonMethodException: [... Exception message was already printed; see it above ...]
	at freemarker.core.MethodCall._eval(MethodCall.java:67)
	at freemarker.core.Expression.eval(Expression.java:101)
	at freemarker.core.DollarVariable.calculateInterpolatedStringOrMarkup(DollarVariable.java:104)
	at freemarker.core.DollarVariable.accept(DollarVariable.java:63)
	at freemarker.core.Environment.visit(Environment.java:335)
	at freemarker.core.Environment.visit(Environment.java:341)
	at freemarker.core.Environment.visit(Environment.java:341)
	at freemarker.core.Environment.process(Environment.java:314)
	at com.chestnut.common.staticize.StaticizeService.process(StaticizeService.java:93)
	at com.chestnut.contentcore.service.impl.PublishServiceImpl.doContentStaticize(PublishServiceImpl.java:631)
	at com.chestnut.contentcore.service.impl.PublishServiceImpl.contentStaticize(PublishServiceImpl.java:595)
	at com.chestnut.contentcore.publish.ContentPublishTask.publish(ContentPublishTask.java:58)
	at com.chestnut.contentcore.publish.PublishTaskReceiver.onMessage(PublishTaskReceiver.java:57)
	at com.chestnut.contentcore.publish.PublishTaskReceiver.onMessage(PublishTaskReceiver.java:37)
	at org.springframework.data.redis.stream.StreamPollTask.deserializeAndEmitRecords(StreamPollTask.java:157)
	at org.springframework.data.redis.stream.StreamPollTask.doLoop(StreamPollTask.java:128)
	at org.springframework.data.redis.stream.StreamPollTask.run(StreamPollTask.java:112)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
	at java.base/java.lang.Thread.run(Thread.java:833)