Remove unused prefix constant
diff --git a/modules/core/src/main/java/org/apache/synapse/config/xml/endpoints/AddressEndpointFactory.java b/modules/core/src/main/java/org/apache/synapse/config/xml/endpoints/AddressEndpointFactory.java
index 30077d2..1bb96a3 100644
--- a/modules/core/src/main/java/org/apache/synapse/config/xml/endpoints/AddressEndpointFactory.java
+++ b/modules/core/src/main/java/org/apache/synapse/config/xml/endpoints/AddressEndpointFactory.java
@@ -62,7 +62,6 @@
  */
 public class AddressEndpointFactory extends DefaultEndpointFactory {
 
-    private static final String SYSTEM_VARIABLE_PREFIX = "$SYSTEM";
     private static final Log LOG = LogFactory.getLog(AddressEndpointFactory.class);
     private static AddressEndpointFactory instance = new AddressEndpointFactory();