@Override
        protected String getDescription() {
          return "DeleteNamespaceProcedure";
        }
Delete an existing Namespace. Only empty Namespaces (no tables) can be removed.
@param nonceGroup Identifier for the source of the request, a client or process.
@param nonce      A unique identifier for this operation from the client or process identified
                  by <code>nonceGroup</code> (the source must ensure each operation gets a
                  unique id).
@return procedure id
hbase-server/src/main/java/org/apache/hadoop/hbase/master/HMaster.java