### Jira - [x] My PR addresses the following [Airflow Jira](https://issues.apache.org/jira/browse/AIRFLOW/) issues and references them in the PR title. For example, "\[AIRFLOW-XXX\] My Airflow PR" - https://issues.apache.org/jira/browse/AIRFLOW-3155 - In case you are fixing a typo in the documentation you can prepend your commit with \[AIRFLOW-XXX\], code changes always need a Jira issue.
### Description Currently the GoogleCloudStorageToGoogleCloudStorageOperator doesn't support filtering objects based on a last modified time/date. This would add the ability to further filter source object(s) to copy/move based on a last modified time threshold (for example, if the objects were updated after the last run at 10:00 yesterday, then copy/move them; otherwise, do not.) ### Tests - [x] My PR adds the following unit tests __OR__ does not need testing for this extremely good reason: test_no_prefix_with_filter_by_last_modified_true_with_false_cond test_execute_no_prefix_with_filter_by_last_modified_false test_no_prefix_with_filter_by_last_modified_true_with_true_cond test_wc_with_filter_by_last_modified_false test_wc_with_filter_by_last_modified_true_with_one_true_cond test_wc_with_filter_by_last_modified_true_with_all_true_cond test_execute_filter_by_last_modified ### Commits - [x] My commits all reference Jira issues in their subject lines, and I have squashed multiple commits if they address the same issue. In addition, my commits follow the guidelines from "[How to write a good git commit message](http://chris.beams.io/posts/git-commit/)": 1. Subject is separated from body by a blank line 1. Subject is limited to 50 characters (not including Jira issue reference) 1. Subject does not end with a period 1. Subject uses the imperative mood ("add", not "adding") 1. Body wraps at 72 characters 1. Body explains "what" and "why", not "how" ### Documentation - [x] In case of new functionality, my PR adds documentation that describes how to use it. - When adding new operators/hooks/sensors, the autoclass documentation generation needs to be added. ### Code Quality - [x] Passes `git diff upstream/master -u -- "*.py" | flake8 --diff` [ Full content available at: https://github.com/apache/incubator-airflow/pull/4008 ] This message was relayed via gitbox.apache.org for devnull@infra.apache.org
