java_gen: fix variable_name for classes
diff --git a/java_gen/java_model.py b/java_gen/java_model.py
index feb3c72..4971d02 100644
--- a/java_gen/java_model.py
+++ b/java_gen/java_model.py
@@ -669,7 +669,7 @@
 
     @property
     def variable_name(self):
-        return self.name[3:]
+        return self.name[2].lower() + self.name[3:]
 
     @property
     def length(self):