Improve NetworkConnectionServiceTest

-            // build the message
-            final StringBuilder msb = new StringBuilder();
-            for (int i = 0; i < size; i++) {
-              msb.append("1");
-            }
-            final String message = msb.toString();
-
+            final String message = StringUtils.repeat('1', size);

+  conn.open();
for (int i = 0; i < numMessages; i++) {
  ...
-  conn.open();
-  conn.write(sb.toString());
+  conn.write(message);
}