Show criteria upon search timeout

src/main/java/com/mailosaur/Messages.java

@@ -6,6 +6,10 @@
 import java.util.List;
 
 import com.google.api.client.http.HttpResponse;
+import com.google.gson.Gson;
+import com.google.gson.JsonObject;
+import com.google.gson.JsonParser;
+import com.google.gson.JsonSerializer;
 import com.mailosaur.models.*;
 
 /**
@@ -335,7 +339,9 @@ public MessageListResult search(MessageSearchParams params, SearchCriteria crite
                 if (params.errorOnTimeout() == false) {
                     return result;
                 }
-                throw new MailosaurException("No matching messages found in time. By default, only messages received in the last hour are checked (use receivedAfter to override this).", "search_timeout");
+
+                String criteriaJson = new Gson().toJson(criteria);
+                throw new MailosaurException("No matching messages found in time. By default, only messages received in the last hour are checked (use receivedAfter to override this). The search criteria used for this query was ["+criteriaJson+"] which timed out after "+params.timeout()+"ms", "search_timeout");
             }
 
             try {