Merge branch 'stable-3.1' into stable-3.2
* stable-3.1: (49 commits)
Add change number to task output
Only copy required folders for testing
Add missing copyright/license header
Use a bash associative array to speedup task tests
plugins/task: Move TaskExpression iteration to Preloader
Add bazel rule for junit tests
Introduce TaskKey, SubSectionKey and FileKey
plugins/task: Fix cache name in Preloader
Only reload nodes when needed
Skip re-expanding properties for local properties
Use a lazy loading task property expansion model
Refresh TaskTree.Nodes when getting them
Cache preloaded tasks
Rename a bunch of TaskTree addNode() methods
Add preload-task to external file tests
Add Root Preload tasks-factory test
Create a TaskExpression with unit tests
Do not modify definition during preload
Return Optional<Task> in Task.Config
Make task config collection fields immutable
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Change-Id: I8686d0ea61437af3ee648ced15ff8789e02e6ec4