Then @dkayiwa @ibacher i think the the immunization resource on https:// qa-refapp.openmrs.org/openmrs/ws/fhir2/R4/Immunization requires this concept CIEL:1421 but there seems to be an issue with it as can be seen in the response below:
{"resourceType":"OperationOutcome","text":{"status":"generated","div":"<div xmlns=\"http://www.w3.org/1999/xhtml\"><h1>Operation Outcome</h1><table border=\"0\"><tr><td style=\"font-weight: bold;\">ERROR</td><td>[]</td><td><pre>The Immunization resource requires a concept mapped to 'CIEL:1421', however either multiple concepts are mapped to that term or not concepts are mapped to that term.</pre></td>\n\t\t\t</tr>\n\t\t</table>\n\t</div>"},"issue":[{"severity":"error","code":"business-rule","diagnostics":"The Immunization resource requires a concept mapped to 'CIEL:1421', however either multiple concepts are mapped to that term or not concepts are mapped to that term."}]}