vxlan: T5429: source-interface is not honored and throws config error

cpo@leaf-02# show interfaces vxlan
+vxlan vxlan1 {
+    mtu 1500
+    parameters {
+        nolearning
+    }
+    port 4789
+    source-interface dum1
+    vni 100
+}

cpo@leaf-02# commit
[ interfaces vxlan vxlan1 ]
Group, remote or source-address must be configured

[[interfaces vxlan vxlan1]] failed

Extend verify() check to also honor source-interface definition.

src/conf_mode/interfaces-vxlan.py

@@ -87,8 +87,8 @@ def verify(vxlan):
             raise ConfigError('Multicast VXLAN requires an underlaying interface')
         verify_source_interface(vxlan)
 
-    if not any(tmp in ['group', 'remote', 'source_address'] for tmp in vxlan):
-        raise ConfigError('Group, remote or source-address must be configured')
+    if not any(tmp in ['group', 'remote', 'source_address', 'source_interface'] for tmp in vxlan):
+        raise ConfigError('Group, remote, source-address or source-interface must be configured')
 
     if 'vni' not in vxlan and 'external' not in vxlan:
         raise ConfigError(