fix gradle config file: java & kotlin compile target jvm

build.gradle

@@ -1,7 +1,8 @@
 buildscript {
     ext {
+        jvm_version = '19'
         kotlin_version = '1.8.20'
-        spring_version = "3.0.5"
+        spring_version = '3.0.5'
     }
 
     repositories {
@@ -47,6 +48,16 @@ subprojects {
         testApi group: 'junit', name: 'junit', version: '4.12'
     }
 
+    /*** 指定 Java & Kotlin 语言编译目标JVM ***/
+    sourceCompatibility = "$jvm_version"
+    targetCompatibility = "$jvm_version"
+    compileKotlin {
+        kotlinOptions.jvmTarget = "$jvm_version"
+    }
+    compileTestKotlin {
+        kotlinOptions.jvmTarget = "$jvm_version"
+    }
+
     publishing {
 //    repositories {
 //        maven {