The is R4 E2M AID is located in https://wiki.o-ran-sc.org/display/RICP/E2+Manager+Interface+Design+-+R4+Draft 

Requirements

• If there is No parameters (RANs doesn’t include or empty) – Access the RAN Nodes, search for at least one who in Connected State. If not Found – Return 404 Not Found with errorCode – 406 and error message “No RAN in Connected State”
• If there is parameters RANs with at least one – Access the RAN Nodes, search for at least one who in Connected State from the list. Ignore RANs that doesn’t exist at all. If not Found any connected state – Return 404 Not Found with errorCode – 406 and error message “No RAN in Connected State”
• If U can’t access the DB properly - Return 500 Bad Request with errorCode – 500 and error message “RNIB error” - take the text  + error code from AID.
• In case SW Exception - - Return 500 Bad Request with errorCode – 501 and error message “Internal Server Error. Please try again later” - take the text  + error code from AID.
• This was a negative flow. See that if request is OK - return 202 Accepted.

Acceptance

Just do the list of negative scenario above and see the result.