add condition on addressPrefix for subnetTika

nested/network.json

@@ -47,10 +47,9 @@
                         }
                     },
                     {
-                        "condition": "[equals(parameters('moodleCommon').tikaService, 'tika')]",
                         "name": "[parameters('moodleCommon').subnetTika]",
                         "properties": {
-                            "addressPrefix": "[parameters('moodleCommon').subnetTikaRange]"
+                            "addressPrefix": "[if(equals(parameters('moodleCommon').tikaService, 'tika'), parameters('moodleCommon').subnetTikaRange, json('null'))]"
                         }
                     },
                     {