TAMAYA-277: Fix Sonar warning.
diff --git a/configured-sysprops/src/main/java/org/apache/tamaya/sysprops/ConfiguredSystemProperties.java b/configured-sysprops/src/main/java/org/apache/tamaya/sysprops/ConfiguredSystemProperties.java
index 7a5cc70..cbac5f4 100644
--- a/configured-sysprops/src/main/java/org/apache/tamaya/sysprops/ConfiguredSystemProperties.java
+++ b/configured-sysprops/src/main/java/org/apache/tamaya/sysprops/ConfiguredSystemProperties.java
@@ -186,7 +186,7 @@
     }
 
     @Override
-    public void loadFromXML(InputStream in) throws IOException {
+    public synchronized void loadFromXML(InputStream in) throws IOException {
         getContextualProperties().loadFromXML(in);
     }