java_gen: make OFFactory be a XidGenerator
diff --git a/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/protocol/XidGenerator.java b/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/protocol/XidGenerator.java
index 65976dc..2ee2764 100644
--- a/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/protocol/XidGenerator.java
+++ b/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/protocol/XidGenerator.java
@@ -1,5 +1,5 @@
 package org.projectfloodlight.openflow.protocol;
 
 public interface XidGenerator {
-    int nextXid();
+    long nextXid();
 }