Enable LoaderIntegrationTests on Java 21

spring-boot-tests/spring-boot-integration-tests/spring-boot-loader-tests/src/intTest/java/org/springframework/boot/loader/LoaderIntegrationTests.java

@@ -44,6 +44,7 @@ import static org.assertj.core.api.Assertions.assertThat;
  * Integration tests loader that supports fat jars.
  *
  * @author Phillip Webb
+ * @author Moritz Halbritter
  */
 @DisabledIfDockerUnavailable
 @DisabledOnOs(os = { OS.LINUX, OS.MAC }, architecture = "aarch64",
@@ -85,6 +86,7 @@ class LoaderIntegrationTests {
 		javaRuntimes.add(JavaRuntime.openJdk(JavaVersion.SEVENTEEN));
 		javaRuntimes.add(JavaRuntime.openJdk(JavaVersion.TWENTY));
 		javaRuntimes.add(JavaRuntime.oracleJdk17());
+		javaRuntimes.add(JavaRuntime.openJdkEarlyAccess(JavaVersion.TWENTY_ONE));
 		return javaRuntimes.stream().filter(JavaRuntime::isCompatible);
 	}
 
@@ -115,6 +117,13 @@ class LoaderIntegrationTests {
 			return this.name;
 		}
 
+		static JavaRuntime openJdkEarlyAccess(JavaVersion version) {
+			String imageVersion = version.toString();
+			DockerImageName image = DockerImageName.parse("openjdk:%s-ea-jdk".formatted(imageVersion));
+			return new JavaRuntime("OpenJDK Early Access " + imageVersion, version,
+					() -> new GenericContainer<>(image));
+		}
+
 		static JavaRuntime openJdk(JavaVersion version) {
 			String imageVersion = version.toString();
 			DockerImageName image = DockerImageName.parse("bellsoft/liberica-openjdk-debian:" + imageVersion);