Read Json stream as UTF-8

Do not (implicitly) rely on Charset.defaultCharset(). RFC 8259
specifies UTF-8 unless in a closed system. Older RFC 7159 and RFC
4627 allowed UTF-8, UTF-16, UTF-32, big or little endian, with or
without BOM.

Change-Id: I33ddfacccc97f81d9eeaf444f734c469028c8214
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>

org.eclipse.tips.json/src/org/eclipse/tips/json/JsonTipProvider.java

diff --git a/org.eclipse.tips.json/src/org/eclipse/tips/json/JsonTipProvider.java b/org.eclipse.tips.json/src/org/eclipse/tips/json/JsonTipProvider.java
index 95d8fc7..ec6312c 100644
--- a/org.eclipse.tips.json/src/org/eclipse/tips/json/JsonTipProvider.java
+++ b/org.eclipse.tips.json/src/org/eclipse/tips/json/JsonTipProvider.java
@@ -18,6 +18,7 @@
 import java.io.InputStreamReader;
 import java.net.MalformedURLException;
 import java.net.URL;
+import java.nio.charset.StandardCharsets;
 import java.text.MessageFormat;
 import java.text.ParseException;
 import java.util.ArrayList;
@@ -105,7 +106,10 @@
 	}
 
 	private JsonObject loadJsonObject() throws IOException {
-		try (InputStream stream = fJsonUrl.openStream(); InputStreamReader reader = new InputStreamReader(stream)) {
+		// RFC 8259: https://tools.ietf.org/html/rfc8259#section-8.1
+		// Json MUST be encoded as UTF-8, unless in a closed system.
+		try (InputStream stream = fJsonUrl.openStream();
+				InputStreamReader reader = new InputStreamReader(stream, StandardCharsets.UTF_8)) {
 			Object result = JsonParser.parseReader(reader);
 			if (result instanceof JsonObject) {
 				return (JsonObject) result;