use scala.util.Properties.javaSpecVersion

Author: xuwei-k

.github/workflows/ci.yml

@@ -20,4 +20,4 @@ jobs:
     - name: install sbt
       run: curl -Ls https://git.io/sbt > ./sbt && chmod 0755 ./sbt
     - name: test
-      run: ./sbt -v -J--enable-preview -Djdk_version=${{matrix.java}} scalafmtCheckAll scalafmtSbtCheck +test
+      run: ./sbt -v -J--enable-preview scalafmtCheckAll scalafmtSbtCheck +test

build.sbt

@@ -1,8 +1,6 @@
 import ReleaseTransformations._
 
-def jdkVersion: String = sys.props.get("jdk_version").flatMap(_.split('-').headOption).getOrElse("15")
-
-javacOptions ++= Seq("--enable-preview", "--release", jdkVersion)
+javacOptions ++= Seq("--enable-preview", "--release", scala.util.Properties.javaSpecVersion)
 
 organization := "com.github.xuwei-k"
 name := "shapeless-java-records"