While building 1.10.0-rc3, I wanted to experiment with the compilation and runtime variants using Java 8 and Java 11. The summary of this experiment was:
Comp: Java 8 Run: Java 8 => SUCCESS Comp: Java 8 Run: Java 11 => SUCCESS Comp: Java 11 Run: Java 8 => FAILURE Comp: Java 11 Run: Java 11 => SUCCESS As introduced in JEP-247 [1], starting with Java 9, javac has the ability to compile to an older Java platform. This was not possible previously without having multiple JDKs installed and specifying the '-bootclasspath' option in javac for your target. The newly introduced "--release" option to Java 9+ javac allows you to specify the target version using the documented API for that platform. This means replacing the '-source' and '-target' parameters with the '--release' option instead. In maven, that manifests itself as a configuration option to the maven-compiler-plugin, which is the 'maven.compiler.release' property. [2] The discussion here would be consideration for using the "release" option as opposed to our current setup which uses "source" and "target". The benefit would be that all the deployment scenarios (above) could result in success. The downside though is that, without other changes, Java 11 would be required to compile NiFi. It would still target Java 8 as a supported runtime (specifying "release=8"), but you'd have to build/compile with Java 11. I don't think this should be a problem, but it's worth discussion. Thanks, Adam [1] https://openjdk.java.net/jeps/247 [2] https://maven.apache.org/plugins/maven-compiler-plugin/compile-mojo.html#release
