fix: prevent hanging by call backgroundResources.close() on stub.close() [ggj]

[miraleung]

Closes #792.

[codecov]

Codecov Report

Merging #804 (e959ac1) into dev/try-catch-list (552af72) will increase coverage by 0.02%.
The diff coverage is 100.00%.

@@                  Coverage Diff                   @@
##           dev/try-catch-list     #804      +/-   ##
======================================================
+ Coverage               91.30%   91.32%   +0.02%     
======================================================
  Files                     140      140              
  Lines                   15012    15050      +38     
  Branches                 1086     1086              
======================================================
+ Hits                    13707    13745      +38     
  Misses                   1009     1009              
  Partials                  296      296              

Impacted Files	Coverage Δ
...poser/common/AbstractServiceStubClassComposer.java	98.46% <100.00%> (+0.10%)	⬆️

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[vam-google]

I was a bit hesitant originally, but giving it a closer look, seems like this PR really does the right thing: close() methods call close() underneath (instead of shutdown(), which was the old behavior). I mean shutdown() must call shutdown() for child resources, close() must call close() for child resources (instead of shutdown()), and this PR brings the generated code to that correct state.

Please address one comment about exception wraping before mergin.

[vam-google]

Looks like this (exception wrapping) exists solely because backgroundResources.close() is checked (throws Exception), but the EchoStub.close()is declared as non-checked, so we need do something like that for things to compile. Either way it will be a breaking behavioral change. To mitigate it, I think we can wrap only what we must (checked exceptions), but throw as is all the unchecked exceptions, so please consider generating somethign like this instead:

   try {
      backgroundResources.close();
    } catch (RungimeException e) {
      thrown e;
    } catch (Exception e) {
      throw new IllegalStateException("Failed to close resource", e);
    }
  }

This will let us to avoid unnecessary exception wrapping, making this change differ less from the previous behavior.

[miraleung]

Done.