Use the bootRun javaLauncher in fork task

Verified in a new Spring initializer project (plus springdoc and plugin)
for both Java and Kotlin.

For Java, choose Java 24 as toolchain version in build.gradle but configure Gradle JVM
to Java 23 or earlier.

For Kotlin, use Java 21 as bytecode version, but for illustrative purposes, downgrade
Gradle JVM to Java 19 for example.

LinkageError, java.lang.UnsupportedClassVersionError occurs in forkedSpringBootRun task
in both cases (but with different encountered versus supported class file versions)

Author: tjog

src/main/kotlin/org/springdoc/openapi/gradle/plugin/OpenApiGradlePlugin.kt

@@ -5,8 +5,10 @@ import org.gradle.api.Plugin
 import org.gradle.api.Project
 import org.gradle.api.Task
 import org.gradle.api.UnknownDomainObjectException
+import org.gradle.api.plugins.JavaPluginExtension
 import org.gradle.api.tasks.TaskProvider
 import org.gradle.internal.jvm.Jvm
+import org.gradle.jvm.toolchain.JavaToolchainService
 import org.springframework.boot.gradle.tasks.run.BootRun
 
 open class OpenApiGradlePlugin : Plugin<Project> {
@@ -110,6 +112,11 @@ open class OpenApiGradlePlugin : Plugin<Project> {
 				?: bootRun.jvmArgs
 			environment = customBootRun.environment.orNull?.takeIf { it.isNotEmpty() }
 				?: bootRun.environment
+
+			// Respect javaLauncher configured for bootRun, so Gradle JVM version
+			// (which may differ) is not used.
+			javaLauncher.set(bootRun.javaLauncher)
+
 			if (Jvm.current().toString().startsWith("1.8")) {
 				killDescendants = false
 			}