AggregateFilter does not properly handle cache timestamp check in Linux

• Type: Bug
• Status: Closed
• Resolution: Fixed
• Affects Version/s: Master
• Fix Version/s: 7.0.0 DXP FP42, 7.0.6 CE GA7, 7.0.0 DXP SP8, 7.0.X, 7.1.0 M2, 7.1.X, Master
• Component/s: Performance > Caching Infrastructure
• Labels:
  • ee-ts
  • liferay-digital-enterprise-70-sp8
  • liferay-fixpack-de-42-7010
• Branch Version/s:
  7.0.x
• Backported to Branch:
  Committed
• Fix Priority: 3
• Git Pull Request: https://github.com/brianchandotcom/liferay-portal/pull/55939

Steps to Reproduce:
1. Start the portal in a Linux environment
2. Access the everything resource URL:

http://localhost:8080/o/frontend-js-web/everything.jsp?browserId=other&themeId=classic_WAR_classictheme&colorSchemeId=01&minifierType=js&minifierBundleId=javascript.everything.files&languageId=en_US&b=7010&t=1513021991893

3. In a terminal run:

stat {tomcat_home}/work/Catalina/localhost/ROOT/aggregate/javascript.everything.files

4. Change the time-stamp from the resource URL (the last query string) and access the resource again:

http://localhost:8080/o/frontend-js-web/everything.jsp?browserId=other&themeId=classic_WAR_classictheme&colorSchemeId=01&minifierType=js&minifierBundleId=javascript.everything.files&languageId=en_US&b=7010&t=1513021991894

5. In the terminal, run the command again

Expected Behavior: Change date does not get updated
Actual Behavior: Change date gets updated

Notes
Unix timestamps truncate the millilseconds portion, however, we are doing a direct comparison in AggregateFilter which causes the cache file to never be utilized:

https://github.com/liferay/liferay-portal/blob/2029efac9154152b124a81e38362697806940ddc/portal-impl/src/com/liferay/portal/servlet/filters/aggregate/AggregateFilter.java#L293