code: private String[] buildColumnsArray(List<TColumn> columns) {
  		String[] columnsArray = new String[columns.size()];
  		for (int i = 0; i < columns.size(); i++) {
  			TColumn column = columns.get(i);
  			columnsArray[i] = column.getName();
  		}
  		return columnsArray;
  	}
docs: Build a columns name array from the list of columns
  
  @param columns
  column list
  @return column names array