SONAR suggestion - problems with string format calls

Change-Id: Ie6b985d2e4db79d6398b17e38a680920f52366b3
diff --git a/protocols/bgp/ctl/src/main/java/org/onosproject/bgp/controller/impl/HexDump.java b/protocols/bgp/ctl/src/main/java/org/onosproject/bgp/controller/impl/HexDump.java
index 0ee620b..777dc61 100644
--- a/protocols/bgp/ctl/src/main/java/org/onosproject/bgp/controller/impl/HexDump.java
+++ b/protocols/bgp/ctl/src/main/java/org/onosproject/bgp/controller/impl/HexDump.java
@@ -40,7 +40,7 @@
                 StringBuilder sb = new StringBuilder();
                 for (int k = 0; (k < 16) && (buff.readableBytes() != 0); ++k) {
                     if (0 == k % 4) {
-                        sb.append(String.format(" ")); // blank after 4 bytes
+                        sb.append(" "); // blank after 4 bytes
                     }
                     sb.append(String.format("%02X ", buff.readByte()));
                 }