I guess the key has been changed due to this line.
public byte[] getBpmnXML(BpmnModel bpmnModel) {
for (Process process : bpmnModel.getProcesses()) {
if (StringUtils.isNotEmpty(process.getId())) {
char firstCharacter = process.getId().charAt(0);
// no digit is allowed as first character
if (Character.isDigit(firstCharacter)) {
process.setId("a" + process.getId());
}
}
}
byte[] xmlBytes = bpmnXMLConverter.convertToXML(bpmnModel);
return xmlBytes;
}