code: public ColumnModel singleUnique(String uniqueName) {
  		makeSureTableModelExist();
  		DialectException.assureNotEmpty(uniqueName, "indexName can not be empty");
  		this.tableModel.unique(uniqueName).columns(this.getColumnName());
  		return this;
  	}
docs: A shortcut method to add a unique constraint for single column, for multiple
  columns index please use tableModel.unique() method