The default set of packages to be staged on a pool of
workers.
Values:
DEFAULT_PACKAGE_SET_UNKNOWN (0):
The default set of packages to stage is
unknown, or unspecified.
DEFAULT_PACKAGE_SET_NONE (1):
Indicates that no packages should be staged
at the worker unless explicitly specified by the
job.
DEFAULT_PACKAGE_SET_JAVA (2):
Stage packages typically useful to workers
written in Java.
DEFAULT_PACKAGE_SET_PYTHON (3):
Stage packages typically useful to workers
written in Python.
