VersionPolicy is the version policy for the repository.
Values:
VERSION_POLICY_UNSPECIFIED (0):
VERSION_POLICY_UNSPECIFIED - the version policy is not
defined. When the version policy is not defined, no
validation is performed for the versions.
RELEASE (1):
RELEASE - repository will accept only Release
versions.
SNAPSHOT (2):
SNAPSHOT - repository will accept only
Snapshot versions.