Issue #35 - use standard charsets

Author: tonicsoft

src/main/java/com/googlecode/protobuf/format/JsonJacksonFormat.java

@@ -36,6 +36,7 @@ SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 import java.io.OutputStreamWriter;
 import java.math.BigInteger;
 import java.nio.charset.Charset;
+import java.nio.charset.StandardCharsets;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Locale;
@@ -146,7 +147,7 @@ public void merge(JsonParser parser,
 
 
     protected JsonGenerator createGenerator(OutputStream output) throws IOException {
-        return createGenerator(output, Charset.forName(JsonEncoding.UTF8.getJavaName()));
+        return createGenerator(output, StandardCharsets.UTF_8);
     }
 
     private JsonGenerator createGenerator(OutputStream output, Charset cs) throws IOException {