Problem

There are some proto files that are differing, for example bigtable/admin/v2 :

Current (wrong) generation output

See googleapis/java-bigtable#2159 for a demo PR

Details

Check googleapis - it has an update_mask entry:
https://github.com/googleapis/googleapis/blob/9868a57470a969ffa1d21194a5c05d7a6e4e98cc/google/bigtable/admin/v2/bigtable_table_admin.proto#L775-L780

Check googleapis-gen - it also has an update_mask entry:
https://github.com/googleapis/googleapis-gen/blob/b983c8f87e6643d9a74d7b8183d66349943b436e/google/bigtable/admin/v2/google-cloud-bigtable-admin-v2-java/proto-google-cloud-bigtable-admin-v2-java/src/main/proto/google/bigtable/admin/v2/bigtable_table_admin.proto#L775-L780

Check java-bigtable - it doesn't have it
https://github.com/googleapis/java-bigtable/blob/27274b4088db707e2a4cd950d61bb14bea1ded3a/proto-google-cloud-bigtable-admin-v2/src/main/proto/google/bigtable/admin/v2/bigtable_table_admin.proto#L772-L776

In owl-bot-copy PRs, the postprocessor doesn't touch the proto
googleapis/java-bigtable@0e95c92#diff-eb0acb7170b49f28d5f2eab282bb756fa72796e8db8cc65547987870ed197d20

• synthtool doesn't have special treatment for bigtable

The googleapis BUILD.bazel looks like it's not doing anything special:

proto_library( name = "admin_proto", srcs = [ "bigtable_instance_admin.proto", "bigtable_table_admin.proto", "common.proto", "instance.proto", "table.proto", "types.proto", ], deps = [ "//google/api:annotations_proto", "//google/api:client_proto", "//google/api:field_behavior_proto", "//google/api:resource_proto", "//google/iam/v1:iam_policy_proto", "//google/iam/v1:policy_proto", "//google/longrunning:operations_proto", "//google/rpc:status_proto", "@com_google_protobuf//:duration_proto", "@com_google_protobuf//:empty_proto", "@com_google_protobuf//:field_mask_proto", "@com_google_protobuf//:timestamp_proto", ], ) 

This is the bigtable/admin/v2 folder:

@JoeWang1127 is this something you came across when dealing with special treatment cases of proto files? Looks like this is something occurring after generating the proto libraries