This will probably be my only Windows and my only Java related blog post ever :(
The JDK version 11 is available from Oracle under a non-open-source license (which you probably don't want), and a GPLv2 license version, https://jdk.java.net/11/.
For Window, you get a .zip file, but no installer. The following has to be done manually:
Windows Registry Editor Version 5.00 [HKEY_LOCAL_MACHINE\SOFTWARE\JavaSoft] [HKEY_LOCAL_MACHINE\SOFTWARE\JavaSoft\Java Runtime Environment] "CurrentVersion"="11.0.1" [HKEY_LOCAL_MACHINE\SOFTWARE\JavaSoft\Java Runtime Environment\11.0.1] "JavaHome"="C:\jdk-11.0.1"