Ensure that closing a JarFile closes all underlying resources

Closes gh-8871

spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/jar/JarFile.java

@@ -298,6 +298,7 @@ public class JarFile extends java.util.jar.JarFile {
 
 	@Override
 	public void close() throws IOException {
+		super.close();
 		this.rootFile.close();
 	}
 

spring-boot-tools/spring-boot-loader/src/test/java/org/springframework/boot/loader/jar/JarFileTests.java

 /*
- * Copyright 2012-2016 the original author or authors.
+ * Copyright 2012-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -469,4 +469,13 @@ public class JarFileTests {
 		}
 	}
 
+	@Test
+	public void jarFileCanBeDeletedOnceItHasBeenClosed() throws Exception {
+		File temp = this.temporaryFolder.newFile();
+		TestJarCreator.createTestJar(temp);
+		JarFile jf = new JarFile(temp);
+		jf.close();
+		assertThat(temp.delete()).isTrue();
+	}
+
 }