feat: Set minimal JVM version for RunServer task

Author: osipxd

src/main/kotlin/BukkitGradlePlugin.kt

@@ -4,14 +4,14 @@ import org.gradle.api.Plugin
 import org.gradle.api.Project
 import org.gradle.api.plugins.JavaPluginExtension
 import org.gradle.api.tasks.compile.JavaCompile
-import org.gradle.jvm.toolchain.JavaLanguageVersion
 import org.gradle.kotlin.dsl.*
 import ru.endlesscode.bukkitgradle.dependencies.Dependencies
 import ru.endlesscode.bukkitgradle.meta.PluginMetaPlugin
 import ru.endlesscode.bukkitgradle.meta.extension.PluginMetaImpl
 import ru.endlesscode.bukkitgradle.meta.util.MinecraftVersion
 import ru.endlesscode.bukkitgradle.meta.util.StringUtils
 import ru.endlesscode.bukkitgradle.meta.util.parsedApiVersion
+import ru.endlesscode.bukkitgradle.meta.util.resolveMinimalJavaVersion
 import ru.endlesscode.bukkitgradle.server.DevServerPlugin
 import ru.endlesscode.bukkitgradle.server.extension.ServerConfigurationImpl
 
@@ -77,14 +77,4 @@ public class BukkitGradlePlugin : Plugin<Project> {
         version < MinecraftVersion.V1_20_5 -> version.withoutPatch().toString()
         else -> version.toString()
     }
-
-    private fun resolveMinimalJavaVersion(version: MinecraftVersion): JavaLanguageVersion = when {
-        // https://minecraft.wiki/w/Java_Edition_1.20.5#General_2
-        version >= MinecraftVersion.V1_20_5 -> JavaLanguageVersion.of(21)
-        // https://minecraft.wiki/w/Java_Edition_1.18#General_2
-        version >= MinecraftVersion.V1_18_0 -> JavaLanguageVersion.of(17)
-        // https://minecraft.wiki/w/Java_Edition_1.17#General_2
-        version >= MinecraftVersion.V1_17_0 -> JavaLanguageVersion.of(16)
-        else -> JavaLanguageVersion.of(8)
-    }
 }

src/main/kotlin/meta/util/MinecraftVersion.kt

@@ -1,5 +1,6 @@
 package ru.endlesscode.bukkitgradle.meta.util
 
+import org.gradle.jvm.toolchain.JavaLanguageVersion
 import ru.endlesscode.bukkitgradle.Bukkit
 
 @JvmInline
@@ -29,3 +30,15 @@ internal value class MinecraftVersion(private val value: Int) : Comparable<Minec
 }
 
 internal val Bukkit.parsedApiVersion get() = apiVersion.map(MinecraftVersion::parse)
+
+internal fun resolveMinimalJavaVersion(version: String) = resolveMinimalJavaVersion(MinecraftVersion.parse(version))
+
+internal fun resolveMinimalJavaVersion(version: MinecraftVersion): JavaLanguageVersion = when {
+    // https://minecraft.wiki/w/Java_Edition_1.20.5#General_2
+    version >= MinecraftVersion.V1_20_5 -> JavaLanguageVersion.of(21)
+    // https://minecraft.wiki/w/Java_Edition_1.18#General_2
+    version >= MinecraftVersion.V1_18_0 -> JavaLanguageVersion.of(17)
+    // https://minecraft.wiki/w/Java_Edition_1.17#General_2
+    version >= MinecraftVersion.V1_17_0 -> JavaLanguageVersion.of(16)
+    else -> JavaLanguageVersion.of(8)
+}

src/main/kotlin/server/DevServerPlugin.kt

@@ -3,14 +3,15 @@ package ru.endlesscode.bukkitgradle.server
 import org.gradle.api.Plugin
 import org.gradle.api.Project
 import org.gradle.api.file.Directory
+import org.gradle.api.plugins.JavaPluginExtension
 import org.gradle.api.provider.Provider
 import org.gradle.api.tasks.TaskContainer
 import org.gradle.api.tasks.TaskProvider
-import org.gradle.kotlin.dsl.apply
-import org.gradle.kotlin.dsl.named
-import org.gradle.kotlin.dsl.register
+import org.gradle.jvm.toolchain.JavaToolchainService
+import org.gradle.kotlin.dsl.*
 import ru.endlesscode.bukkitgradle.Bukkit
 import ru.endlesscode.bukkitgradle.bukkit
+import ru.endlesscode.bukkitgradle.meta.util.resolveMinimalJavaVersion
 import ru.endlesscode.bukkitgradle.server.extension.ServerConfiguration
 import ru.endlesscode.bukkitgradle.server.task.CreateIdeaGradleRunConfiguration
 import ru.endlesscode.bukkitgradle.server.task.PrepareServer
@@ -52,12 +53,31 @@ public class DevServerPlugin : Plugin<Project> {
             }
         }
 
+        // RunPaperPlugin uses afterEvaluate under the hood, so we have to use afterEvaluate
+        // to set our conventions after theirs
+        project.afterEvaluate { configureDefaultJvmForServer() }
+
         val prepareServer = registerPrepareServerTask(runServer)
         runServer.configure { dependsOn(prepareServer) }
 
         registerBuildIdeRunTask(runServer)
     }
 
+    private fun Project.configureDefaultJvmForServer() {
+        val toolchains = project.extensions.findByType<JavaToolchainService>() ?: return
+        val spec = the<JavaPluginExtension>().toolchain
+
+        tasks.withType<RunServer>().configureEach {
+            javaLauncher.convention(
+                toolchains.launcherFor {
+                    languageVersion.convention(version.map(::resolveMinimalJavaVersion))
+                    implementation.convention(spec.implementation)
+                    vendor.convention(spec.vendor)
+                }
+            )
+        }
+    }
+
     private fun Project.resolveConfiguredServerDir(): Provider<Directory>? {
         val deprecated = DeprecatedServerProperties(rootDir, providers)