4.3.x Branch Does Not Build Using Java 25

[ryanjbaxter]

This is because the maven-kotlin-plugin version 1.9.25 does not support Java 25. We need to figure out a way to configure the build so it does not fail

[olegz]

@ryanjbaxter @spencergibb

This does not appear to be possible with Maven plugin (while it is with Gradle). The crash happens unconditionally inside the plugin's own startup code — it is not a compilation setting you can configure around.

Here is exactly what happens when Maven starts on JDK 25:

kotlin-maven-plugin loads
└─ JavaVersion.current() ← reads System.getProperty("java.version") = "25.0.2"
└─ JavaVersion.parse("25.0.2") ← throws IllegalArgumentException
This fires before any user configuration, jvmTarget, toolchain, or compiler argument is read. There is no plugin parameter that prevents it.

[ERROR] Failed to execute goal org.jetbrains.kotlin:kotlin-maven-plugin:1.9.25:compile (compile) on project spring-cloud-function-context: Compilation failure
[ERROR] java.lang.IllegalArgumentException: 25.0.2
[ERROR] 	at com.intellij.util.lang.JavaVersion.parse(JavaVersion.java:305)
[ERROR] 	at com.intellij.util.lang.JavaVersion.current(JavaVersion.java:174)
[ERROR] 	at org.jetbrains.kotlin.cli.jvm.modules.JavaVersionUtilsKt.isAtLeastJava9(javaVersionUtils.kt:11)
[ERROR] 	at org.jetbrains.kotlin.cli.jvm.modules.CoreJrtFileSystem$Companion$globalJrtFsCache$1.invoke(CoreJrtFileSystem.kt:83)
[ERROR] 	at org.jetbrains.kotlin.cli.jvm.modules.CoreJrtFileSystem$Companion$globalJrtFsCache$1.invoke(CoreJrtFileSystem.kt:74)
. . .