Add updateContentMd5 method in interface.

This method will help caching handling by checking
that cached conversion result is computed from same data
as the one carried by document.


git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@35205 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5/interfaces/cached_convertable.py

@@ -90,3 +90,9 @@ class ICachedConvertable(Interface):
 
     **kw -- conversion parameters
     """
+
+  def updateContentMd5():
+    """
+    Udpate MD5 hash of non converted data in order
+    to check that returned cached result was computed from same origin.
+    """