command: ./gradlew assemble
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 
then i looked for jdk12
but jdk12 has reached end of support. here is the link
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?