The value of msapTlsPlcySplitHorizonGrp specifies the name of the
split-horizon group for the MSAP.
If the name specified does not correspond to a tlsShgInfoEntry
for the VPLS service, the creation of the MSAP will fail.
Additionally, if msapTlsPlcySplitHorizonGrp is set to a new value,
the sapSplitHorizonGrp object for any existing MSAPs created by
this policy will not be updated.