Unable to work on user tasks with dynamic form if a task variable is set as java.util.Date type in BPM Suite 6.4.x

Issue

• When trying to work on a human task in Business Central the error below is displayed and in the log file we see an exception. We use the default user interface, no customizations have been made.

  ## Console error:
  
  Something wrong happened. Unexpected error loading task form: Failed to process form template
  

  ## server.log error:
  
  14:55:28,873 ERROR [freemarker.runtime] (http-127.0.0.1:8080-4) Template processing error: "Can't convert the date to string, because it is not known which parts of the date variable are in use. Use ?date, ?time or ?datetime built-in, or ?string.\u003Cformat> or ?string(format) built-in with this date.": freemarker.template.TemplateModelException: Can't convert the date to string, because it is not known which parts of the date variable are in use. Use ?date, ?time or ?datetime built-in, or ?string.<format> or ?string(format) built-in with this date.
  at freemarker.core.Environment.formatDate(Environment.java:776) [freemarker-2.3.19.jar:2.3.19]
  ...
  at freemarker.template.Template.process(Template.java:259) [freemarker-2.3.19.jar:2.3.19]
  at org.jbpm.kie.services.impl.form.provider.FreemakerFormProvider.render(FreemakerFormProvider.java:45) [jbpm-kie-services-6.5.0.Final-redhat-16.jar:6.5.0.Final-redhat-16]
  

• Unable to view user task form in business-central if a task variable set as java.util.Date type is set and using default task form in BPM Suite 6.4.x;