fix(samples): dataset getcreatetime (#866)

Author: Praful Makani

samples/snippets/src/main/java/com/example/bigquery/ResourceCleanUp.java

@@ -47,13 +47,13 @@ public static void main(String[] args) {
     // clean up stale test datasets
     Page<Dataset> datasets = bigquery.listDatasets(PROJECT_ID, DatasetListOption.pageSize(1000));
     for (Dataset dataset : datasets.getValues()) {
+      dataset = dataset.reload();
       String datasetName = dataset.getDatasetId().getDataset();
       if ((datasetName.contains("CREATE_DATASET_AWS_TEST_")
-          || datasetName.contains("MY_DATASET_")
-          || datasetName.contains("gcloud_test_")
-          || datasetName.contains("SHARED_DATASET_TEST_"))
-      // && dataset.getCreationTime() > sixHourAgo
-      ) {
+              || datasetName.contains("MY_DATASET_")
+              || datasetName.contains("gcloud_test_")
+              || datasetName.contains("SHARED_DATASET_TEST_"))
+          && dataset.getCreationTime() > sixHourAgo) {
         System.out.format("\tDeleting Dataset: %s\n", datasetName);
         bigquery.delete(
             DatasetId.of(PROJECT_ID, datasetName), BigQuery.DatasetDeleteOption.deleteContents());