feat(generator): allow Any to Struct/Value migration and update compute protos

Author: colinmoy

generator/internal/discovery_type_vertex.cc

@@ -547,6 +547,13 @@ StatusOr<int> DiscoveryTypeVertex::GetFieldNumber(
     }
 
     if (field_descriptor->name() == field_name && type_name != field_type) {
+      // Allow migration of google.protobuf.Any to google.protobuf.Struct or
+      // google.protobuf.Value.
+      if (absl::StrContains(type_name, "google.protobuf.Any") &&
+          (absl::StrContains(field_type, "google.protobuf.Struct") ||
+           absl::StrContains(field_type, "google.protobuf.Value"))) {
+        return field_descriptor->number();
+      }
       // Existing field type has changed. This is a breaking change.
       return internal::InvalidArgumentError(absl::StrFormat(
           "Message: %s has field: %s whose type has changed "

protos/google/cloud/compute/v1/internal/common_019.proto

@@ -21,7 +21,7 @@ syntax = "proto3";
 
 package google.cloud.cpp.compute.v1;
 
-import "google/protobuf/any.proto";
+import "google/protobuf/struct.proto";
 
 message BulkInsertOperationStatus {
   // [Output Only] Count of VMs successfully created so far.
@@ -524,7 +524,7 @@ message Status {
 
   // A list of messages that carry the error details.  There is a common set of
   // message types for APIs to use.
-  repeated google.protobuf.Any details = 2 [json_name = "details"];
+  repeated google.protobuf.Struct details = 2 [json_name = "details"];
 
   // A developer-facing error message, which should be in English. Any
   // user-facing error message should be localized and sent in the