To reproduce,

1. Create an empty BigQuery table without any field on its schema. Let's say it's table "tableA" on dataset "dataset1".
2. Running this code fails the assertion.

    BigQuery bigQuery = BigQueryOptions.getDefaultInstance().getService();
    Table table = bigQuery.getTable("dataset1", "tableA");
    Assert.assertNotNull(table.getDefinition().getSchema());

Is this expected behavior? Because we in fact can't create a TableDefinition with null schema as it's null-checked in com.google.cloud.bigquery.TableDefinition.Builder.

    /**
     * Sets the table schema.
     */
    public B setSchema(Schema schema) {
      this.schema = checkNotNull(schema);
      return self();
    }

I think BigQuery.getTable on a table with empty schema should return a Schema instance with no field within its TableDefinition.