Adding grpc-alts as a runtime dependency causes the maven-flatten-plugin to add the compile time dependencies in the flattened pom. As far as I can tell, grpc-alts is (currently) only used for testing, so adding it as a test scoped dependency seems to make more sense to me.

Fixes the build error in googleapis/java-spanner-jdbc#293

@mohanli-ml Is there a specific reason that grpc-alts was added as a runtime dependency instead of a test dependency?

Codecov Report

Merging #757 (543148b) into master (aa701f5) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master     #757   +/-   ##
=========================================
  Coverage     85.15%   85.15%           
  Complexity     2562     2562           
=========================================
  Files           142      142           
  Lines         13960    13960           
  Branches       1331     1331           
=========================================
  Hits          11887    11887           
- Misses         1513     1514    +1     
+ Partials        560      559    -1     

Impacted Files	Coverage Δ	Complexity Δ
.../google/cloud/spanner/SpannerExceptionFactory.java	82.47% <0.00%> (-2.07%)	46.00% <0.00%> (-1.00%)
...ud/spanner/SessionPoolAsyncTransactionManager.java	87.30% <0.00%> (+1.58%)	13.00% <0.00%> (+2.00%)

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@mohanli-ml Won't we need alts for the usage of direct path in production? Or is this only necessary for the tests?

@mohanli-ml Won't we need alts for the usage of direct path in production? Or is this only necessary for the tests?

If it is needed for production: Why does it need to explicitly be added as a runtime dependency, as it is already a compile dependency (it's already included transitively by a couple of other dependencies)?

@olavloite I wonder why didn't we add it in the test scope instead.

@olavloite I wonder why didn't we add it in the test scope instead.

@thiagotnunes I'm not exactly sure what you mean in this case. This PR puts it in the test scope. The current situation is that it is explicitly added as a runtime dependency, and that is what is causing some trouble downstream with the JDBC driver.

Yes, sorry, what I meant was why didn't we use the test scope in the first place instead of the runtime scope.

@olavloite @thiagotnunes DirectPath use ALTS for authentication, but in this repo we only use it for tests, so I think use test scope should be good. Thanks!