RestUrls.createRelativeResourceUrl(RestUrls.URL_PROCESS_INSTANCE_VARIABLE_COLLECTION, processInstance.getId()));
httpPost.setEntity(new StringEntity(requestNode.toString()));
closeResponse(executeRequest(httpPost, HttpStatus.SC_BAD_REQUEST));
// Test passing in empty array
requestNode.removeAll();
httpPost = new HttpPost(SERVER_URL_PREFIX +
RestUrls.createRelativeResourceUrl(RestUrls.URL_PROCESS_INSTANCE_VARIABLE_COLLECTION, processInstance.getId()));
httpPost.setEntity(new StringEntity(requestNode.toString()));
closeResponse(executeRequest(httpPost, HttpStatus.SC_BAD_REQUEST));