Use Java 8 for examples project

docs/modules/guides/examples/docs-modules-guides-examples.gradle

@@ -1,12 +1,10 @@
 plugins {
-    //id 'org.springframework.boot' version '2.6.2'
-    //id 'io.spring.dependency-management' version '1.0.11.RELEASE'
     id 'java'
 }
 
 group = 'org.springframework.security'
 version = '0.0.1-SNAPSHOT'
-sourceCompatibility = '11'
+sourceCompatibility = '1.8'
 
 repositories {
     mavenCentral()

docs/modules/guides/examples/src/main/java/sample/jpa/JpaOAuth2AuthorizationService.java

@@ -234,7 +234,7 @@ public class JpaOAuth2AuthorizationService implements OAuth2AuthorizationService
 
 	private Map<String, Object> parseMap(String data) {
 		try {
-			return this.objectMapper.readValue(data, new TypeReference<>() {
+			return this.objectMapper.readValue(data, new TypeReference<Map<String, Object>>() {
 			});
 		} catch (Exception ex) {
 			throw new IllegalArgumentException(ex.getMessage(), ex);

docs/modules/guides/examples/src/main/java/sample/jpa/JpaRegisteredClientRepository.java

@@ -135,7 +135,7 @@ public class JpaRegisteredClientRepository implements RegisteredClientRepository
 
 	private Map<String, Object> parseMap(String data) {
 		try {
-			return this.objectMapper.readValue(data, new TypeReference<>() {
+			return this.objectMapper.readValue(data, new TypeReference<Map<String, Object>>() {
 			});
 		} catch (Exception ex) {
 			throw new IllegalArgumentException(ex.getMessage(), ex);

docs/modules/guides/examples/src/test/java/sample/jpa/JpaTests.java

@@ -82,7 +82,7 @@ import static sample.util.RegisteredClients.messagingClient;
 public class JpaTests {
 
 	private static final Pattern HIDDEN_STATE_INPUT_PATTERN = Pattern.compile(".+<input type=\"hidden\" name=\"state\" value=\"([^\"]+)\">.+");
-	private static final TypeReference<Map<String, Object>> TOKEN_RESPONSE_TYPE_REFERENCE = new TypeReference<>() {
+	private static final TypeReference<Map<String, Object>> TOKEN_RESPONSE_TYPE_REFERENCE = new TypeReference<Map<String, Object>>() {
 	};
 
 	public final SpringTestContext spring = new SpringTestContext(this);