add PGV validation on enum (#9722)

Signed-off-by: Asra Ali <asraa@google.com>

Mirrored from https://github.com/envoyproxy/envoy @ c2936d30778f9cda14bc2ef848f8158dc6996b61

envoy/api/v2/route/route_components.proto

@@ -77,7 +77,7 @@ message VirtualHost {
 
   // Specifies the type of TLS enforcement the virtual host expects. If this option is not
   // specified, there is no TLS requirement for the virtual host.
-  TlsRequirementType require_tls = 4;
+  TlsRequirementType require_tls = 4 [(validate.rules).enum = {defined_only: true}];
 
   // A list of virtual clusters defined for this virtual host. Virtual clusters
   // are used for additional statistics gathering.

envoy/config/route/v3/route_components.proto

@@ -81,7 +81,7 @@ message VirtualHost {
 
   // Specifies the type of TLS enforcement the virtual host expects. If this option is not
   // specified, there is no TLS requirement for the virtual host.
-  TlsRequirementType require_tls = 4;
+  TlsRequirementType require_tls = 4 [(validate.rules).enum = {defined_only: true}];
 
   // A list of virtual clusters defined for this virtual host. Virtual clusters
   // are used for additional statistics gathering.