config: Minor cleanup

- Stop implicitly assuming locales in String.format
- Cleanup method visibilities
- Improve uses of Integer methods
- Remove unused getToken method

Signed-off-by: Harsh Shandilya <me@msfjarvis.dev>

app/src/main/java/com/wireguard/config/Attribute.java

@@ -7,6 +7,7 @@ import java.lang.reflect.Method;
 import java.net.InetAddress;
 import java.util.HashMap;
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
@@ -88,17 +89,13 @@ enum Attribute {
     }
 
     public String composeWith(final int value) {
-        return String.format("%s = %d%n", token, value);
+        return String.format(Locale.getDefault(), "%s = %d%n", token, value);
     }
 
     public <T> String composeWith(final List<T> value) {
         return String.format("%s = %s%n", token, listToString(value));
     }
 
-    public String getToken() {
-        return token;
-    }
-
     public String parse(final CharSequence line) {
         final Matcher matcher = pattern.matcher(line);
         return matcher.matches() ? matcher.group(1) : null;