update deprecated field in EnvoyFilter example (#2713)

Author: ufUNnxagpM

networking/v1alpha3/envoy_filter.pb.go

@@ -139,19 +139,20 @@ import "networking/v1alpha3/sidecar.proto";
 //        name: envoy.filters.http.lua
 //        typed_config:
 //           "@type": "type.googleapis.com/envoy.extensions.filters.http.lua.v3.Lua"
-//           inlineCode: |
-//             function envoy_on_request(request_handle)
-//               -- Make an HTTP call to an upstream host with the following headers, body, and timeout.
-//               local headers, body = request_handle:httpCall(
-//                "lua_cluster",
-//                {
-//                 [":method"] = "POST",
-//                 [":path"] = "/acl",
-//                 [":authority"] = "internal.org.net"
-//                },
-//               "authorize call",
-//               5000)
-//             end
+//           defaultSourceCode:
+//             inlineString: |
+//               function envoy_on_request(request_handle)
+//                 -- Make an HTTP call to an upstream host with the following headers, body, and timeout.
+//                 local headers, body = request_handle:httpCall(
+//                  "lua_cluster",
+//                  {
+//                   [":method"] = "POST",
+//                   [":path"] = "/acl",
+//                   [":authority"] = "internal.org.net"
+//                  },
+//                 "authorize call",
+//                 5000)
+//               end
 //   # The second patch adds the cluster that is referenced by the lua code
 //   # cds match is omitted as a new cluster is being added
 //   - applyTo: CLUSTER