public BulkResponse terminateWorkflows(List<String> workflowIds, String reason) {
        Validate.isTrue(!workflowIds.isEmpty(), "workflow id cannot be blank");
        return postForEntity(
                "workflow/bulk/terminate",
                workflowIds,
                new Object[] {"reason", reason},
                BulkResponse.class);
    }
Terminates the execution of all given workflows instances

@param workflowIds the ids of the workflows to be terminated
@param reason the reason to be logged and displayed
@return the {@link BulkResponse} contains bulkErrorResults and bulkSuccessfulResults
client/src/main/java/com/netflix/conductor/client/http/WorkflowClient.java