SAI_API_MPLS not supported for Mellanox/Nvidia Spectrum chips

[odd22]

I try to enable MPLS on interface of a Spectrum 2 ASICs, but this failed with following messages telling that SAI_API_MPLS is not yet supported:

Jun 28 15:45:40.679835 nvidia1 DEBUG bgp#staticroutebfd: Received message : '('Ethernet32', 'SET', (('mpls', 'enable'),))'
Jun 28 15:45:40.680775 nvidia1 DEBUG bgp#staticroutebfd: Received message : '('Ethernet0', 'SET', (('mpls', 'enable'),))'
Jun 28 15:45:41.514624 nvidia1 DEBUG bgp#bgpcfgd: Received message : '('Ethernet32', 'SET', (('mpls', 'enable'),))'
Jun 28 15:45:41.515600 nvidia1 DEBUG bgp#bgpcfgd: Received message : '('Ethernet0', 'SET', (('mpls', 'enable'),))'
Jun 28 15:45:46.315845 nvidia1 WARNING syncd#SDK: [SAI_INTERFACE_QUERY_ETH.WARNING] mlnx_sai_interfacequery_eth.c[304]- sai_log_set_eth: SAI_API_MPLS not implemented
Jun 28 15:45:47.768530 nvidia1 WARNING syncd#SDK: [SAI_INTERFACE_QUERY_ETH.WARNING] mlnx_sai_interfacequery_eth.c[304]- sai_log_set_eth: SAI_API_MPLS not implemented
Jun 28 15:45:47.935562 nvidia1 WARNING syncd#SDK: [SAI_INTERFACE_QUERY_ETH.WARNING] mlnx_sai_interfacequery_eth.c[304]- sai_log_set_eth: SAI_API_MPLS not implemented
Jun 28 15:45:48.100702 nvidia1 WARNING syncd#SDK: [SAI_INTERFACE_QUERY_ETH.WARNING] mlnx_sai_interfacequery_eth.c[304]- sai_log_set_eth: SAI_API_MPLS not implemented
Jun 28 15:45:48.265288 nvidia1 WARNING syncd#SDK: [SAI_INTERFACE_QUERY_ETH.WARNING] mlnx_sai_interfacequery_eth.c[304]- sai_log_set_eth: SAI_API_MPLS not implemented
Jun 28 15:45:50.685139 nvidia1 WARNING syncd#SDK: [SAI_UTILS.WARNING] mlnx_sai_utils.c[1732]- check_attribs_metadata: Not implemented attribute SAI_ROUTER_INTERFACE_ATTR_ADMIN_MPLS_
STATE (vendor data not found)
Jun 28 15:45:50.685178 nvidia1 ERR syncd#SDK: :- processQuadEvent: attr: SAI_ROUTER_INTERFACE_ATTR_ADMIN_MPLS_STATE: true
Jun 28 15:45:50.685421 nvidia1 ERR swss#orchagent: :- setRouterIntfsMpls: Failed to set router interface Ethernet0 MPLS to enable, rv:-196608