Update the build.gradle.kts to be more strict with the javaVersion requirement (#8032)

Author: jwren

build.gradle.kts

@@ -60,9 +60,13 @@ println("untilBuild: $untilBuildInput")
 println("javaVersion: $javaVersion")
 println("group: $group")
 
-var jvmVersion = JvmTarget.JVM_17
-if (javaVersion == "21") {
+var jvmVersion: JvmTarget
+if (javaVersion == "17") {
+  jvmVersion = JvmTarget.JVM_17
+} else if (javaVersion == "21") {
   jvmVersion = JvmTarget.JVM_21
+} else {
+  throw IllegalArgumentException("javaVersion must be defined in the product matrix as either \"17\" or \"21\", but is not for $ideaVersion")
 }
 kotlin {
   compilerOptions {
@@ -71,9 +75,13 @@ kotlin {
   }
 }
 
-var javaCompatibilityVersion = JavaVersion.VERSION_17
-if (javaVersion == "21") {
+var javaCompatibilityVersion: JavaVersion
+if (javaVersion == "17") {
+  javaCompatibilityVersion = JavaVersion.VERSION_17
+} else if (javaVersion == "21") {
   javaCompatibilityVersion = JavaVersion.VERSION_21
+} else {
+  throw IllegalArgumentException("javaVersion must be defined in the product matrix as either \"17\" or \"21\", but is not for $ideaVersion")
 }
 java {
   sourceCompatibility = javaCompatibilityVersion

flutter-idea/build.gradle.kts

@@ -38,9 +38,13 @@ val untilBuildInput = providers.gradleProperty("untilBuild").get()
 val javaVersion = providers.gradleProperty("javaVersion").get()
 group = "io.flutter"
 
-var jvmVersion = JvmTarget.JVM_17
-if (javaVersion == "21") {
+var jvmVersion: JvmTarget
+if (javaVersion == "17") {
+  jvmVersion = JvmTarget.JVM_17
+} else if (javaVersion == "21") {
   jvmVersion = JvmTarget.JVM_21
+} else {
+  throw IllegalArgumentException("javaVersion must be defined in the product matrix as either \"17\" or \"21\", but is not for $ideaVersion")
 }
 kotlin {
   compilerOptions {
@@ -49,9 +53,13 @@ kotlin {
   }
 }
 
-var javaCompatibilityVersion = JavaVersion.VERSION_17
-if (javaVersion == "21") {
+var javaCompatibilityVersion: JavaVersion
+if (javaVersion == "17") {
+  javaCompatibilityVersion = JavaVersion.VERSION_17
+} else if (javaVersion == "21") {
   javaCompatibilityVersion = JavaVersion.VERSION_21
+} else {
+  throw IllegalArgumentException("javaVersion must be defined in the product matrix as either \"17\" or \"21\", but is not for $ideaVersion")
 }
 java {
   sourceCompatibility = javaCompatibilityVersion

flutter-studio/build.gradle.kts

@@ -39,9 +39,13 @@ val untilBuildInput = providers.gradleProperty("untilBuild").get()
 val javaVersion = providers.gradleProperty("javaVersion").get()
 group = "io.flutter"
 
-var jvmVersion = JvmTarget.JVM_17
-if (javaVersion == "21") {
+var jvmVersion: JvmTarget
+if (javaVersion == "17") {
+  jvmVersion = JvmTarget.JVM_17
+} else if (javaVersion == "21") {
   jvmVersion = JvmTarget.JVM_21
+} else {
+  throw IllegalArgumentException("javaVersion must be defined in the product matrix as either \"17\" or \"21\", but is not for $ideaVersion")
 }
 kotlin {
   compilerOptions {
@@ -50,9 +54,13 @@ kotlin {
   }
 }
 
-var javaCompatibilityVersion = JavaVersion.VERSION_17
-if (javaVersion == "21") {
+var javaCompatibilityVersion: JavaVersion
+if (javaVersion == "17") {
+  javaCompatibilityVersion = JavaVersion.VERSION_17
+} else if (javaVersion == "21") {
   javaCompatibilityVersion = JavaVersion.VERSION_21
+} else {
+  throw IllegalArgumentException("javaVersion must be defined in the product matrix as either \"17\" or \"21\", but is not for $ideaVersion")
 }
 java {
   sourceCompatibility = javaCompatibilityVersion