Set proper jvmTarget for projects

libraries/commonConfiguration.gradle

@@ -43,6 +43,9 @@ ext.configureJvmProject = { Project project ->
 
 ext.configureJvm6Project = { Project project ->
     project.configure(project) {
+        project.ext.jvmTarget = "1.6"
+        project.ext.javaHome = JDK_16
+
         task sourcesJar(type: Jar, dependsOn: classes) {
             classifier = 'sources'
             from sourceSets.main.kotlin

libraries/stdlib/jre7/build.gradle

@@ -4,6 +4,7 @@ apply plugin: 'kotlin'
 
 configureJvm6Project(project)
 configurePublishing(project)
+ext.javaHome = JDK_17
 
 dependencies {
     compile project(':kotlin-stdlib')

libraries/stdlib/jre8/build.gradle

@@ -4,6 +4,7 @@ apply plugin: 'kotlin'
 
 configureJvm6Project(project)
 configurePublishing(project)
+ext.javaHome = JDK_18
 
 dependencies {
     compile project(':kotlin-stdlib')