Nexus Repository Manager 3 on Windows bundles its own JRE. If you want to update to a later version of Java you will need to override the version shipped with Nexus.
You can do that as follows:
- In the installation directory there is a .install4j directory
- In this directory create a file named pref_jre.cfg if it does not exist.
- In the file put the complete path to the root directory of the Java installation you want to use.
You will need to restart Nexus for this change to take effect.