If a resource is found with the identifier specified in the query parameters, updates part of that resource by applying the operations specified in a JSON Patch document. Implements the FHIR standard conditional patch interaction, limited to searching by resource identifier. DSTU2 doesn't define a conditional patch method, but the server supports it in the same way it supports STU3. Search term for identifier should be in the pattern identifier=system|value or identifier=value - similar to the search method on resources with a specific identifier. If the search criteria identify more than one match, the request returns a 412 Precondition Failed error. If the search criteria doesn't identify any matches, the request returns a 404 Not Found error. The request body must contain a JSON Patch document, and the request headers must contain Content-Type: application/json-patch+json. On success, the response body contains a JSON-encoded representation of the updated resource, including the server-assigned version ID. Errors generated by the FHIR store contain a JSON-encoded OperationOutcome resource describing the reason for the error. If the request cannot be mapped to a valid API method on a FHIR store, a generic GCP error might be returned instead. For samples that show how to call conditionalPatch, see Conditionally patching a FHIR resource.