Can not build source code without suitable jdk

ES 7.2
jdk 11
command: ./gradlew assemble
os: macOS

error message
the compiler java.home must be set to a JDK installation directory for Java 12 but is [/Library/Java/JavaVirtualMachines/jdk-11.0.5.jdk/Contents/Home] corresponding to [11]

then i looked for jdk12
but jdk12 has reached end of support. here is the link
https://www.oracle.com/technetwork/java/javase/downloads/jdk12-downloads-5295953.html

then i installed jdk 13. The result was entirely predictable
java.lang.IllegalArgumentException: Unsupported class file major version 57

my question is how can i build the source code now?

@dadoonet @cufflinks can you give me some help?

Read this and specifically the "Also be patient" part.

It's fine to answer on your own thread after 2 or 3 days (not including weekends) if you don't have an answer.

I don't have the answer as I did not build elasticsearch recently. Someone from elasticsearch dev team might be able to answer hopefully.