From f7d1f968b9c227d842759df71c1a0877658f6f2b Mon Sep 17 00:00:00 2001
From: Andy Wilkinson <awilkinson@pivotal.io>
Date: Wed, 1 Oct 2014 10:09:30 +0100
Subject: [PATCH] Improve error message when JarFile encounters a compressed
 nested jar

Closes gh-1643
---
 .../java/org/springframework/boot/loader/jar/JarFile.java   | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/jar/JarFile.java b/spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/jar/JarFile.java
index 59316f8550..9785800df2 100644
--- a/spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/jar/JarFile.java
+++ b/spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/jar/JarFile.java
@@ -375,8 +375,10 @@ public class JarFile extends java.util.jar.JarFile implements Iterable<JarEntryD
 	private JarFile createJarFileFromFileEntry(JarEntryData sourceEntry)
 			throws IOException {
 		if (sourceEntry.getMethod() != ZipEntry.STORED) {
-			throw new IllegalStateException("Unable to open nested compressed entry "
-					+ sourceEntry.getName());
+			throw new IllegalStateException("Unable to open nested entry '"
+					+ sourceEntry.getName() + "'. It has been compressed and nested "
+					+ "jar files must be stored without compression. Please check the "
+					+ "mechanism used to create your executable jar file");
 		}
 		return new JarFile(this.rootFile, this.pathFromRoot + "!/"
 				+ sourceEntry.getName(), sourceEntry.getData());