Fix Checkstyle

Author: jzheaux

servlet/spring-boot/java/saml2/identity-provider/src/main/java/example/IdentityProviderTestExecutionListener.java

@@ -20,7 +20,6 @@
 import java.net.ServerSocket;
 
 import org.testcontainers.containers.ComposeContainer;
-import org.testcontainers.containers.DockerComposeContainer;
 
 import org.springframework.core.io.ClassPathResource;
 import org.springframework.test.context.TestContext;