PostModelOutputsRequest.newBuilder().setModel() doesn't work

[peterlitvak]

When the PostModelOutputsRequest is constructed like this:

PostModelOutputsRequest.newBuilder()
            .setModelId(model.getId())
            .setVersionId(model.getModelVersion().getId())
            .addAllInputs(inputs)
            .build()

the execution of the request works as expected, however if it is constructed like this:

PostModelOutputsRequest.newBuilder()
            .setModel(model)
            .addAllInputs(inputs)
            .build()

the request fails with Model '' doesn't exist message.