private Operation getExistingOperation(Map<HttpMethod, Operation> operationMap, RequestMethod requestMethod) {
		Operation existingOperation = null;
		if (!CollectionUtils.isEmpty(operationMap)) {
			// Get existing operation definition
			switch (requestMethod) {
				case GET:
					existingOperation = operationMap.get(HttpMethod.GET);
					break;
				case POST:
					existingOperation = operationMap.get(HttpMethod.POST);
					break;
				case PUT:
					existingOperation = operationMap.get(HttpMethod.PUT);
					break;
				case DELETE:
					existingOperation = operationMap.get(HttpMethod.DELETE);
					break;
				case PATCH:
					existingOperation = operationMap.get(HttpMethod.PATCH);
					break;
				case HEAD:
					existingOperation = operationMap.get(HttpMethod.HEAD);
					break;
				case OPTIONS:
					existingOperation = operationMap.get(HttpMethod.OPTIONS);
					break;
				default:
					// Do nothing here
					break;
			}
		}
		return existingOperation;
	}
Gets existing operation.

@param operationMap  the operation map
@param requestMethod the request method
@return the existing operation
springdoc-openapi-starter-common/src/main/java/org/springdoc/api/AbstractOpenApiResource.java