ECMS-5819: CLONE - Error showing PDF file in a linked detail page

Fix description:
  - Check the validity of jcr:lastModified before access to the property
ECMS-5819: CLONE - Error showing PDF file in a linked detail page

Fix description:
  - Separate redundant code into a public function of Utils

Conflicts:
	core/services/src/main/java/org/exoplatform/services/cms/impl/Utils.java