The JDK has just moved to GitHub through project Skara. I am moving to a new laptop. So it is time to revisit building OpenJDK and OpenJFX (on Windows 10 64bits).
Create a C:\dev\ directory
Download and install Cygwin
select the following packagesautoconf
make
zip
unzip
Download and install Git
Either from Git for Windows or via Cygwin (the later may be more compatible with the build)
Download the current OpenJDK and extract it to C:\dev\jdk-14.0.2