Missing vspansession object

When iterating through a vim.dvs.VmwareDistributedVirtualSwitch object captured through viewManager.CreateContainerView() class, the vSpanSession list is always empty, even for DVSs which have multiple Mirroring Sessions.

Additionally, performing a ReconfigureDvs_Task() method on the DVS with a vspanConfigSpec "add" does not effectively get performed in vCenter. This has been tested on VC6.5 and 6.7 using the latest 6.7.1 pyvmomi codebase.
---GIST---

content = vmSI.RetrieveContent()
switch = get_obj(content, [vim.dvs.VmwareDistributedVirtualSwitch], "vds1")
vspan_spec = vim.dvs.VmwareDistributedVirtualSwitch.VspanConfigSpec()
vspan_sess_spec = vim.dvs.VmwareDistributedVirtualSwitch.VspanSession()
vspan_sess_spec.name = "Test Session"
vspan_sess_spec.description = "This is a test session"
vspan_sess_spec.enabled = True
vspan_sess_spec.sessionType = \     vim.dvs.VmwareDistributedVirtualSwitch.VspanSessionType.remoteMirrorDest
vspan_sess_spec.stripOriginalVlan = False
vspan_sess_spec.normalTrafficAllowed = True

# Set the source VLAN
source_rx = vim.dvs.VmwareDistributedVirtualSwitch.VspanPorts()
source_rx.vlans = [1234]
source_tx = vim.dvs.VmwareDistributedVirtualSwitch.VspanPorts()
source_tx.vlans = [1234]
vspan_sess_spec.sourcePortReceived = source_rx
#vspan_sess_spec.sourcePortTransmitted = source_tx

#Set the dest port
dest = vim.dvs.VmwareDistributedVirtualSwitch.VspanPorts()
dest.portKey = ['7']
vspan_sess_spec.destinationPort = dest

# Add the new spec
vspan_spec.operation = vim.ConfigSpecOperation.add

vspan_spec.vspanSession = vspan_sess_spec

#Get the current switch spec
switch_spec = switch.ConfigSpec()
switch_spec.configVersion = switch.config.configVersion
switch_spec.vspanConfigSpec = [vspan_spec]
switch_spec.name = "vds1"
switch_spec.description ="Help!!"

running_task = switch.ReconfigureDvs_Task(switch_spec)

Start with vim.dvs.VmwareDistributedVirtualSwitch, RetrieveContent(), CreateContainerView(), and the vspanSession and ReconfigureDvs_Task entry points shown in the reproduction. Compare the captured session list and the add vspanConfigSpec behavior on the stated vCenter versions; done means existing sessions are exposed and the added session is applied by vCenter.