Customers using Tomcat 8.5 and configuring the Liferay platform with URLs that have a leading period (.) may encounter the following error:
java.lang.IllegalArgumentException: An invalid domain [.example.com] was specified for this cookie
session.cookie.use.full.hostname property is described as follows:
Set this to true to use the full hostname for cookie domain values. By default the domain is trimmed to use only the root domain to allow cross domain logins.