Add include-code extension setup for docs

Closes gh-17160

Author: rwinch

docs/antora.yml

@@ -16,3 +16,5 @@ asciidoc:
     gh-old-samples-url: 'https://github.com/spring-projects/spring-security/tree/5.4.x/samples'
     gh-samples-url: "https://github.com/spring-projects/spring-security-samples/tree/{gh-tag}"
     gh-url: "https://github.com/spring-projects/spring-security/tree/{gh-tag}"
+    include-java: 'example$docs-src/test/java/org/springframework/security/docs'
+    include-kotlin: 'example$docs-src/test/kotlin/org/springframework/security/kt/docs'

docs/modules/ROOT/examples/docs-src

@@ -0,0 +1 @@
+../../../src

docs/spring-security-docs.gradle

@@ -1,7 +1,10 @@
+import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
+
 plugins {
 	id 'org.antora' version '1.0.0'
 	id 'io.spring.antora.generate-antora-yml' version '0.0.1'
 	id 'io.spring.convention.repository'
+	id 'kotlin'
 }
 
 apply plugin: 'io.spring.convention.docs'
@@ -33,10 +36,23 @@ tasks.register("generateAntoraResources") {
 
 dependencies {
 	testImplementation platform(project(':spring-security-dependencies'))
+	testImplementation project(':spring-security-config')
+	testImplementation project(path : ':spring-security-config', configuration : 'tests')
+	testImplementation project(':spring-security-test')
 	testImplementation 'com.unboundid:unboundid-ldapsdk'
 	testImplementation libs.webauthn4j.core
+	testImplementation 'org.jetbrains.kotlin:kotlin-reflect'
+	testImplementation 'org.jetbrains.kotlin:kotlin-stdlib-jdk8'
 	testImplementation 'org.apache.directory.server:apacheds-core'
 	testImplementation 'org.springframework:spring-core'
+	testImplementation 'org.springframework:spring-test'
+
+	testImplementation 'org.springframework:spring-webmvc'
+	testImplementation 'jakarta.servlet:jakarta.servlet-api'
+	testImplementation "org.junit.jupiter:junit-jupiter-api"
+	testImplementation "org.junit.jupiter:junit-jupiter-params"
+	testImplementation "org.junit.jupiter:junit-jupiter-engine"
+	testRuntimeOnly 'org.junit.platform:junit-platform-launcher'
 }
 
 def generateAttributes() {
@@ -78,3 +94,16 @@ def resolvedVersions(Configuration configuration) {
 				.resolvedArtifacts
 				.collectEntries { [(it.name + '-version'): it.moduleVersion.id.version] }
 }
+
+test {
+	useJUnitPlatform()
+}
+
+tasks.withType(KotlinCompile).configureEach {
+	kotlinOptions {
+		languageVersion = "1.7"
+		apiVersion = "1.7"
+		freeCompilerArgs = ["-Xjsr305=strict", "-Xsuppress-version-warnings"]
+		jvmTarget = "17"
+	}
+}