public Builder clearUserIdToUnshareWith() {
            copyOnWrite();
            instance.clearUserIdToUnshareWith();
            return this;
        }
<code>optional int64 user_id_to_unshare_with = 4;</code>

@return This builder for chaining.
turms-client-kotlin/src/main/java/im/turms/client/model/proto/request/storage/UpdateMessageAttachmentInfoRequest.java