code: @Override
  	public Response deleteFile(String CorpNum, int ItemCode, String MgtKey,
  			String FileID) throws PopbillException {
  		
  		return deleteFile(CorpNum, ItemCode, MgtKey, FileID, null);
  	}
docs: /* (non-Javadoc)
  @see com.popbill.api.StatementService#deleteFile(java.lang.String, java.number.Integer, java.lang.String, java.lang.String)