Revert "Omit jar: prefix from jarFileUrl"

Restore previous behavior where JarFile URLs are always prefixed with
"jar:". I believe that the prefix is required in order to remain
compatible with standard JAR URLs.

This reverts commit 825fc2f7.

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

@@ -63,12 +63,12 @@ class JarURLConnection extends java.net.JarURLConnection {
 		 * sensible for #getJarFileURL().
 		 */
 		if (separator + SEPARATOR.length() != spec.length()) {
-			this.jarFileUrl = new URL(spec);
+			this.jarFileUrl = new URL("jar:" + spec);
 			this.jarEntryName = spec.substring(separator + 2);
 		}
 		else {
 			// The root of the archive (!/)
-			this.jarFileUrl = new URL(spec.substring(0, separator));
+			this.jarFileUrl = new URL("jar:" + spec.substring(0, separator));
 		}
 	}
 

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

@@ -150,7 +150,7 @@ public class JarFileTests {
 		assertThat(jarURLConnection.getContentLength(), greaterThan(1));
 		assertThat(jarURLConnection.getContent(), sameInstance((Object) this.jarFile));
 		assertThat(jarURLConnection.getContentType(), equalTo("x-java/jar"));
-		assertThat(jarURLConnection.getJarFileURL().toString(), equalTo("file:"
+		assertThat(jarURLConnection.getJarFileURL().toString(), equalTo("jar:file:"
 				+ this.rootJarFile));
 	}
 
@@ -216,8 +216,8 @@ public class JarFileTests {
 				+ "!/nested.jar!/"));
 		JarURLConnection conn = (JarURLConnection) url.openConnection();
 		assertThat(conn.getJarFile(), sameInstance(nestedJarFile));
-		assertThat(conn.getJarFileURL().toString(),
-				equalTo("file:" + this.rootJarFile.getPath() + "!/nested.jar"));
+		assertThat(conn.getJarFileURL().toString(), equalTo("jar:file:"
+				+ this.rootJarFile.getPath() + "!/nested.jar"));
 	}
 
 	@Test