Versions of ITMS prior to 8.5 RU2 (ITMS 8.5 RU2 Release Notes) are dependent on the Java 8 JRE. See more as well under KB 173264 "Using Java with the Symantec Management Platform after January 2019"
Prior to ITMS 8.5 RU2 release, the Java 8 JRE must be present on the Notification Server in order to install ITMS. Customers are responsible for installing and the Java 8 JRE and keeping it up to date. Oracle requires that customers obtain a subscription to receive future updates to the Java 8 JRE used for commercial purposes.
ITMS 8.5 RU2 includes components that are part of the open source version of the Java 11 JDK. Those components are installed as part of ITMS 8.5 RU2, eliminating the need for customers to install Java. No subscription is required to obtain updates to the open source version of the Java JDK: