docs: @Override
  	public Response attachStatement(String CorpNum, int ItemCode, String MgtKey,
  				int SubItemCode, String SubMgtKey) throws PopbillException{
  		DocRequest request = new DocRequest();
  		request.ItemCode = SubItemCode;
  		request.MgtKey = SubMgtKey;
  				
  		String PostData = toJsonString(request);
  		
  		return httppost("/Statement/" + ItemCode + "/" + MgtKey + "/AttachStmt/",
  				CorpNum, PostData, null, Response.class);
  		
  	}