Sanitize query: preserve keys without values

app/src/main/java/eu/faircode/email/UriHelper.java

@@ -419,31 +419,44 @@ public class UriHelper {
             path = path.toLowerCase(Locale.ROOT);
 
         boolean first = "www.facebook.com".equals(host);
-        for (String key : url.getQueryParameterNames()) {
-            // https://en.wikipedia.org/wiki/UTM_parameters
-            // https://docs.oracle.com/en/cloud/saas/marketing/eloqua-user/Help/EloquaAsynchronousTrackingScripts/EloquaTrackingParameters.htm
-            String lkey = key.toLowerCase(Locale.ROOT);
-            if (PARANOID_QUERY.contains(lkey) ||
-                    lkey.startsWith("utm_") ||
-                    lkey.startsWith("elq") ||
-                    ((host != null && host.endsWith("facebook.com")) &&
-                            !first &&
-                            FACEBOOK_WHITELIST_PATH.contains(path) &&
-                            !FACEBOOK_WHITELIST_QUERY.contains(lkey)) ||
-                    ("store.steampowered.com".equals(host) &&
-                            "snr".equals(lkey)))
-                changed = true;
-            else if (!TextUtils.isEmpty(key))
-                for (String value : url.getQueryParameters(key)) {
-                    Log.i("Query " + key + "=" + value);
-                    Uri suri = Uri.parse(value);
+        String q = url.getEncodedQuery();
+        if (q != null) {
+            StringBuilder sb = new StringBuilder();
+            for (String kv : q.split("&")) {
+                int eq = kv.indexOf('=');
+                String key = (eq < 0 ? kv : kv.substring(0, eq));
+                String value = (eq < 0 ? null : kv.substring(eq + 1));
+
+                // https://en.wikipedia.org/wiki/UTM_parameters
+                // https://docs.oracle.com/en/cloud/saas/marketing/eloqua-user/Help/EloquaAsynchronousTrackingScripts/EloquaTrackingParameters.htm
+                String lkey = key.toLowerCase(Locale.ROOT);
+                if (PARANOID_QUERY.contains(lkey) ||
+                        lkey.startsWith("utm_") ||
+                        lkey.startsWith("elq") ||
+                        ((host != null && host.endsWith("facebook.com")) &&
+                                !first &&
+                                FACEBOOK_WHITELIST_PATH.contains(path) &&
+                                !FACEBOOK_WHITELIST_QUERY.contains(lkey)) ||
+                        ("store.steampowered.com".equals(host) &&
+                                "snr".equals(lkey)))
+                    changed = true;
+                else if (!TextUtils.isEmpty(key)) {
+                    Uri suri = Uri.parse(key);
                     if (suri != null && isHyperLink(suri)) {
                         Uri s = sanitize(context, suri);
                         return (s == null ? suri : s);
                     }
-                    builder.appendQueryParameter(key, value);
+                    if (sb.length() > 0)
+                        sb.append('&');
+                    sb.append(key);
+                    if (value != null) {
+                        sb.append('=').append(value);
+                    }
                 }
-            first = false;
+                first = false;
+            }
+            if (sb.length() > 0)
+                builder.encodedQuery(sb.toString());
         }
 
         return (changed ? builder.build() : null);