feat: api endpoints and xml sync for contingents data

src/BusProNet/XmlParser/AbstractParser.php

@@ -9,6 +9,15 @@ abstract class AbstractParser
 {
     use TypeConversionTrait;
 
+    protected function getIntOrNullAttribute(?string $value): ?int
+    {
+        if (null === $value || '' === $value) {
+            return null;
+        }
+
+        return (int) $value;
+    }
+
     protected function getStringOrNullValue(Crawler $node): ?string
     {
         return 0 < $node->count() ? $node->text() : null;