key during previous mojo execution.true if file or folder identified by relpath has
changed since last build.true if the file has changed since last build or is not
under basedir.true if any file or folder identified by relpaths has
changed since last build.true if this build context is incremental.basedir for files and directories
deleted since last build.file.basedir.key with specified value
in the build context.setThreadBuildContext(BuildContext).