Note that this goes as Vertex AI in cloud.google.com:

https://github.com/googleapis/googleapis/tree/master/google/cloud/aiplatform/v1
https://cloud.google.com/vertex-ai/docs/reference/rpc/google.cloud.aiplatform.v1

It is possible that this is a large library that requires a hand-crafted layer. The first step is to find out if this is true (talk to other language teams), and if that is the case just close it.