[Gradle] KotlinJvmCompilerOptions: Use JvmTarget.DEFAULT as default value for jvmTarget

KTIJ-24976

generators/tests/org/jetbrains/kotlin/generators/arguments/DefaultValues.kt

@@ -24,6 +24,7 @@ open class DefaultValues(
     val defaultValue: String,
     val type: KType,
     val kotlinOptionsType: KType,
+    val prettyDefaultValue: String? = null,
     val possibleValues: List<String>? = null,
     val fromKotlinOptionConverterProp: String? = null,
     val toKotlinOptionConverterProp: String? = null,
@@ -78,16 +79,17 @@ open class DefaultValues(
     )
 
     object JvmTargetVersions : DefaultValues(
-        "null",
-        typeOf<JvmTargetDsl?>(),
+        "org.jetbrains.kotlin.gradle.dsl.JvmTarget.DEFAULT",
+        typeOf<JvmTargetDsl>(),
         typeOf<String?>(),
         possibleValues = JvmTarget.supportedValues().map { "\"${it.description}\"" },
         fromKotlinOptionConverterProp = """
         if (this != null) ${typeOf<JvmTargetDsl>()}.fromTarget(this) else null
         """.trimIndent(),
         toKotlinOptionConverterProp = """
-        this?.target
-        """.trimIndent()
+        this.target
+        """.trimIndent(),
+        prettyDefaultValue = "\"${JvmTarget.DEFAULT}\""
     )
 
     object JsEcmaVersions : DefaultValues(

generators/tests/org/jetbrains/kotlin/generators/arguments/GenerateGradleOptions.kt

@@ -878,7 +878,7 @@ private fun Printer.generateOptionDeprecation(property: KProperty1<*, *>) {
 private fun Printer.generateDoc(property: KProperty1<*, *>) {
     val description = property.findAnnotation<Argument>()!!.description
     val possibleValues = property.gradleValues.possibleValues
-    val defaultValue = property.gradleDefaultValue
+    val defaultValue = property.gradleValues.prettyDefaultValue ?: property.gradleValues.defaultValue
 
     println("/**")
     println(" * ${description.replace("\n", " ")}")

generators/tests/org/jetbrains/kotlin/generators/arguments/jvmTargetGenerator.kt

@@ -28,6 +28,8 @@ internal fun generateJvmTarget(
                 println("fun fromTarget(target: String): JvmTarget =")
                 println("    JvmTarget.values().firstOrNull { it.target == target }")
                 println("        ?: throw IllegalArgumentException(\"Unknown Kotlin JVM target: ${'$'}target\")")
+                println()
+                println("val DEFAULT = ${JvmTarget.DEFAULT.name}")
             }
             println("}")
         }