Merge branch '2.2.x'

Closes gh-21450

Author: wilkinsona

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/web/embedded/undertow/UndertowServletWebServerFactoryTests.java

@@ -39,6 +39,7 @@
 import org.apache.http.HttpResponse;
 import org.apache.jasper.servlet.JspServlet;
 import org.awaitility.Awaitility;
+import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.Test;
 import org.mockito.InOrder;
 
@@ -74,6 +75,13 @@ protected UndertowServletWebServerFactory getFactory() {
 		return new UndertowServletWebServerFactory(0);
 	}
 
+	@AfterEach
+	void awaitClosureOfSslRelatedInputStreams() {
+		// https://issues.redhat.com/browse/UNDERTOW-1705
+		File resource = new File(this.tempDir, "test.txt");
+		Awaitility.await().atMost(Duration.ofSeconds(30)).until(() -> (!resource.isFile()) || resource.delete());
+	}
+
 	@Test
 	void errorPage404() throws Exception {
 		AbstractServletWebServerFactory factory = getFactory();