Version 1.4.0

• Added a series of batch and streaming example pipelines in a mobile gaming domain that illustrate some advanced topics, including windowing and triggers.
• Added support for Combine functions to access pipeline options and side inputs through a context. See GlobalCombineFn and PerKeyCombineFn for further details.
• Modified ParDo.withSideInputs() such that successive calls are cumulative.
• Modified automatic coder detection of Protocol Buffer messages; such classes now have their coders provided automatically.
• Added support for limiting the number of results returned by DatastoreIO.Source. However, when this limit is set, the operation that reads from Cloud Datastore is performed by a single worker rather than executing in parallel across the worker pool.
• Modified definition of PaneInfo.{EARLY, ON_TIME, LATE} so that panes with only late data are always LATE, and an ON_TIME pane can never cause a later computation to yield a LATE pane.
• Modified GroupByKey to drop late data when that late data arrives for a window that has expired. An expired window means the end of the window is passed by more than the allowed lateness.
• When using GlobalWindows, you are no longer required to specify withAllowedLateness(), since no data is ever dropped.
• Added support for obtaining the default project ID from the default project configuration produced by newer versions of the gcloud utility. If the default project configuration does not exist, Dataflow reverts to using the old project configuration generated by older versions of the gcloud utility.