Fix the build against JDK 20 (#3323)

When using JDK 20, the following error would occur when attempting to
build or run tests:

```
Execution failed for task ':codegen-client:compileKotlin'.
> Inconsistent JVM-target compatibility detected for tasks 'compileJava' (20) and 'compileKotlin' (11).
```

This PR explicitly sets the Java source and target versions to fix this
error.

----

_By submitting this pull request, I confirm that you can use, modify,
copy, and redistribute this contribution, under the terms of your
choice._

aws/rust-runtime/build.gradle.kts

@@ -12,6 +12,11 @@ group = "software.amazon.aws.rustruntime"
 
 version = "0.0.3"
 
+java {
+    sourceCompatibility = JavaVersion.VERSION_11
+    targetCompatibility = JavaVersion.VERSION_11
+}
+
 tasks.jar {
     from("./") {
         include("aws-inlineable/src/*.rs")

aws/sdk-adhoc-test/build.gradle.kts

@@ -12,6 +12,11 @@ plugins {
     id("software.amazon.smithy")
 }
 
+java {
+    sourceCompatibility = JavaVersion.VERSION_11
+    targetCompatibility = JavaVersion.VERSION_11
+}
+
 val smithyVersion: String by project
 val defaultRustDocFlags: String by project
 val properties = PropertyRetriever(rootProject, project)

aws/sdk-codegen/build.gradle.kts

@@ -30,6 +30,11 @@ dependencies {
     implementation("software.amazon.smithy:smithy-aws-endpoints:$smithyVersion")
 }
 
+java {
+    sourceCompatibility = JavaVersion.VERSION_11
+    targetCompatibility = JavaVersion.VERSION_11
+}
+
 tasks.compileKotlin {
     kotlinOptions.jvmTarget = "11"
 }

aws/sdk/build.gradle.kts

@@ -18,6 +18,11 @@ plugins {
     id("software.amazon.smithy")
 }
 
+java {
+    sourceCompatibility = JavaVersion.VERSION_11
+    targetCompatibility = JavaVersion.VERSION_11
+}
+
 configure<software.amazon.smithy.gradle.SmithyExtension> {
     smithyBuildConfigs = files(layout.buildDirectory.file("smithy-build.json"))
     allowUnknownTraits = true

codegen-client/build.gradle.kts

@@ -34,6 +34,11 @@ dependencies {
     testImplementation("software.amazon.smithy:smithy-validation-model:$smithyVersion")
 }
 
+java {
+    sourceCompatibility = JavaVersion.VERSION_11
+    targetCompatibility = JavaVersion.VERSION_11
+}
+
 tasks.compileKotlin {
     kotlinOptions.jvmTarget = "11"
 }

codegen-core/build.gradle.kts

@@ -97,6 +97,11 @@ val generateSmithyRuntimeCrateVersion by tasks.registering {
     }
 }
 
+java {
+    sourceCompatibility = JavaVersion.VERSION_11
+    targetCompatibility = JavaVersion.VERSION_11
+}
+
 tasks.compileKotlin {
     kotlinOptions.jvmTarget = "11"
     dependsOn(generateSmithyRuntimeCrateVersion)

codegen-server/build.gradle.kts

@@ -32,6 +32,11 @@ dependencies {
     testImplementation("software.amazon.smithy:smithy-validation-model:$smithyVersion")
 }
 
+java {
+    sourceCompatibility = JavaVersion.VERSION_11
+    targetCompatibility = JavaVersion.VERSION_11
+}
+
 tasks.compileKotlin { kotlinOptions.jvmTarget = "11" }
 
 // Reusable license copySpec

codegen-server/python/build.gradle.kts

@@ -32,6 +32,11 @@ dependencies {
     testImplementation("software.amazon.smithy:smithy-validation-model:$smithyVersion")
 }
 
+java {
+    sourceCompatibility = JavaVersion.VERSION_11
+    targetCompatibility = JavaVersion.VERSION_11
+}
+
 tasks.compileKotlin { kotlinOptions.jvmTarget = "11" }
 
 // Reusable license copySpec

codegen-server/typescript/build.gradle.kts

@@ -29,6 +29,11 @@ dependencies {
     implementation("software.amazon.smithy:smithy-protocol-test-traits:$smithyVersion")
 }
 
+java {
+    sourceCompatibility = JavaVersion.VERSION_11
+    targetCompatibility = JavaVersion.VERSION_11
+}
+
 tasks.compileKotlin { kotlinOptions.jvmTarget = "11" }
 
 // Reusable license copySpec

rust-runtime/build.gradle.kts

@@ -13,6 +13,11 @@ group = "software.amazon.rustruntime"
 
 version = "0.0.3"
 
+java {
+    sourceCompatibility = JavaVersion.VERSION_11
+    targetCompatibility = JavaVersion.VERSION_11
+}
+
 tasks.jar {
     from("./") {
         include("inlineable/src/")