Remove sloppy java with enterprise java horrors

Since the amount of mind numbing boiler plate has been increased, this
must be the proper way to do things.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

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

@@ -1,5 +1,7 @@
 package com.wireguard.config;
 
+import android.text.TextUtils;
+
 import java.util.HashMap;
 import java.util.Map;
 import java.util.regex.Matcher;
@@ -43,10 +45,22 @@ enum Attribute {
         return KEY_MAP.get(SEPARATOR_PATTERN.split(line)[0]);
     }
 
+    public static String listToString(final String[] list) {
+        return TextUtils.join(", ", list);
+    }
+
+    public static String[] stringToList(final String string) {
+        return string.trim().split("\\s*,\\s*");
+    }
+
     public String composeWith(final Object value) {
         return String.format("%s = %s%n", token, value);
     }
 
+    public String composeWith(final String[] value) {
+        return String.format("%s = %s%n", token, listToString(value));
+    }
+
     public String getToken() {
         return token;
     }
@@ -55,4 +69,9 @@ enum Attribute {
         final Matcher matcher = pattern.matcher(line);
         return matcher.matches() ? matcher.group(1) : null;
     }
+
+    public String[] parseList(final CharSequence line) {
+        final Matcher matcher = pattern.matcher(line);
+        return matcher.matches() ? stringToList(matcher.group(1)) : null;
+    }
 }