The result of dis.getMessageDigest().digest() must be returned here. Otherwise, this method will lose its meaning.

Change-Id: I356a47386bde4c39eb5e1e95a3f7036a38137acd
diff --git a/protocols/openflow/ctl/src/main/java/org/onosproject/openflow/controller/impl/Controller.java b/protocols/openflow/ctl/src/main/java/org/onosproject/openflow/controller/impl/Controller.java
index cb6df8d4..6cf1ddc 100644
--- a/protocols/openflow/ctl/src/main/java/org/onosproject/openflow/controller/impl/Controller.java
+++ b/protocols/openflow/ctl/src/main/java/org/onosproject/openflow/controller/impl/Controller.java
@@ -321,7 +321,8 @@
                 while (dis.read(buffer) > 0) {
                     // nothing to do :)
                 }
-                dis.getMessageDigest().digest();
+                is.close();
+                return dis.getMessageDigest().digest();
             } catch (NoSuchAlgorithmException ignored) {
             } catch (IOException e) {
                 log.info("Error reading file file: {}", filepath);