Make `loader` Windows compatible

The encoding of UTF-8 (et al.) chars in the
JarUrlConnection has to be made explicit, otherwise
Wdinows apparently does not pick the default(?).

Fixes gh-711, Fixes gh-753

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

@@ -20,9 +20,9 @@ import java.io.ByteArrayOutputStream;
 import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.io.InputStream;
-import java.io.UnsupportedEncodingException;
 import java.net.MalformedURLException;
 import java.net.URL;
+import java.nio.charset.Charset;
 import java.util.jar.Manifest;
 
 /**
@@ -169,7 +169,6 @@ class JarURLConnection extends java.net.JarURLConnection {
 		if ((length == 0) || (source.indexOf('%') < 0)) {
 			return source;
 		}
-		try {
 		ByteArrayOutputStream bos = new ByteArrayOutputStream(length);
 		for (int i = 0; i < length; i++) {
 			int ch = source.charAt(i);
@@ -183,11 +182,8 @@ class JarURLConnection extends java.net.JarURLConnection {
 			}
 			bos.write(ch);
 		}
-			return new String(bos.toByteArray(), "UTF-8");
-		}
-		catch (UnsupportedEncodingException ex) {
-			throw new IllegalStateException(ex);
-		}
+		return new String(bos.toByteArray(), Charset.defaultCharset());
+
 	}
 
 	private static char decodeEscapeSequence(String source, int i) {