bpmn2 which has Multi-Instance sub process was created by Business Central process designer and this repository was cloned from Business Central to JBDS. After that when modifying something and saving it by JBDS, several errors relevant to Multi-Instance properties appears.
After correcting these errors by resetting these properties and setting appropriate data type, these changes were pushed back from JBDS to Business Central. When opening the modified process in Business Central, MI data Input and MI data output are not set.