Issue #144 (Add last_modified to WSF_SKELETON_HANDLER)

library/server/wsf/policy_driven/wsf_get_helper.e

@@ -49,6 +49,10 @@ feature {NONE} -- Implementation
 			if attached a_handler.etag (req) as l_etag then
 				a_header.put_header_key_value ({HTTP_HEADER_NAMES}.header_etag, l_etag)
 			end
+			if attached a_handler.last_modified (req) as l_last_modified then
+				l_dt := (create {HTTP_DATE}.make_from_date_time (l_last_modified)).rfc1123_string
+				a_header.put_header_key_value ({HTTP_HEADER_NAMES}.header_last_modified, l_dt)
+			end
 			res.put_header_text (a_header.string)
 			if l_ok then
 				if l_chunked then

library/server/wsf/policy_driven/wsf_skeleton_handler.e

@@ -166,6 +166,16 @@ feature -- Access
 			req_attached: req /= Void
 		deferred
 		end
+	
+	last_modified (req: WSF_REQUEST): detachable DATE_TIME
+			-- When representation of resource selected in `req' was last modified;
+			-- SHOULD be set whenever it can reasonably be determined.
+		note
+			specification: "https://tools.ietf.org/html/rfc7232#section-2.2.1"
+		require
+			req_attached: req /= Void
+		deferred
+		end
 
 	modified_since (req: WSF_REQUEST; a_date_time: DATE_TIME): BOOLEAN
 			-- Has resource requested in `req' been modified since `a_date_time' (UTC)?