Vision: Operation returned from 'purge_product: raises TypeError in 'done'.

[dizcology]

Environment details

1. Vision API, Product Search, Purge Product
2. OSX
3. 2.7.14
4. google-cloud-vision 0.39.0

Steps to reproduce

1. Run tests or either of the purge product samples from this PR: Purge products GoogleCloudPlatform/python-docs-samples#2349
2. The LRO fails at operation.done()

Code example

see PR linked above.

Stack trace

Traceback (most recent call last):
  File "/Users/yuhanliu/projects/dpe-github/python-docs-samples/vision/cloud-client/product_search/product_in_product_set_management_test.py", line 88, in test_purge_products_in_product_set
    PROJECT_ID, LOCATION, PRODUCT_SET_ID, force=True)
  File "/Users/yuhanliu/projects/dpe-github/python-docs-samples/vision/cloud-client/product_search/product_in_product_set_management.py", line 153, in purge_products_in_product_set
    if operation.done():
  File "/Users/yuhanliu/.virtualenvs/vision-ga/lib/python2.7/site-packages/google/api_core/operation.py", line 162, in done
    self._refresh_and_update()
  File "/Users/yuhanliu/.virtualenvs/vision-ga/lib/python2.7/site-packages/google/api_core/operation.py", line 154, in _refresh_and_update
    self._set_result_from_operation()
  File "/Users/yuhanliu/.virtualenvs/vision-ga/lib/python2.7/site-packages/google/api_core/operation.py", line 131, in _set_result_from_operation
    self._result_type, self._operation.response
  File "/Users/yuhanliu/.virtualenvs/vision-ga/lib/python2.7/site-packages/google/api_core/protobuf_helpers.py", line 69, in from_any_pb
    any_pb.__class__.__name__, pb_type.__name__
TypeError: Could not convert Any to Empty

[tseaver]

@dizcology At the point that the exception is raised, can you print out the repr of self.operation.response?

[dizcology]

Thanks @tseaver

When the exception is raised I got this:

ipdb> pp self.operation.response
type_url: "type.googleapis.com/google.cloud.vision.v1.PurgeProductsRequest"
value: "\n-projects/rising-sea-112358/locations/us-west1\030\001 \001"

ipdb> pp type(self.operation.response)
<class 'google.protobuf.any_pb2.Any'>

it might be that the library was trying to convert the response to type Empty?

[tseaver]

@dizcology Looks to me like the .proto for the PurgeProducts RPC is missing the comment markup to indicate the type of the response. E.g., see the .proto for the ImportProductSets RPC, which contains this line:

  // `Operation.response` contains `ImportProductSetsResponse`. (results)

[dizcology]

Thanks @tseaver - does this mean that the comment markup is used in GAPIC library generation for specifying the message types?

[tseaver]

@dizcology I'm not sure: the code which actually parses all that out (in repo https://github.com/googleapis/gapic-generator/) is too arcane for me to read.

[tseaver]

@lukesneeringer, @busunkim96 Can one of you confirm that the comment in the .proto file is used to generate the response type for LRO-returning RPCs?