feat: introduce TransactionOptions and UpdateOptions

[olavloite]

Adds TransactionOptions and UpdateOptions for read/write transactions and statements. These can be used in the future to specify options to affect how transactions and statements will be executed.

These changes can be used as the basis for #676 and #576 to ensure both changes use the same approach, and to prevent enormous merge conflicts.

[mayurkale22]

I like this PR, this will certainly simplify #676 and #576. Thank you so much for doing this!

[mayurkale22]

Can this be just TransactionOption instead of Options?

[olavloite]

That would be possible (assuming you mean TransactionOption...), but I would prefer to keep this as the Options object. This makes it a required argument, making it less likely to be missed by accident as it will cause a compile error if you don't supply an Options object. If we change it to TransactionOption... it would not cause a compile time error if we forget to pass in the options somewhere.

[mayurkale22]

Hmm, makes sense.

[codecov]

Codecov Report

Merging #716 (ae2cf93) into master (f14f7c9) will increase coverage by 0.08%.
The diff coverage is 88.34%.

@@ Coverage Diff @@ ## master #716 +/- ## ============================================ + Coverage 85.03% 85.12% +0.08%  - Complexity 2553 2561 +8  ============================================ Files 142 142 Lines 13930 13952 +22 Branches 1326 1331 +5 ============================================ + Hits 11846 11877 +31  + Misses 1527 1515 -12  - Partials 557 560 +3 

Impacted Files	Coverage Δ	Complexity Δ
...rc/main/java/com/google/cloud/spanner/Options.java	85.48% <40.00%> (-3.99%)	67.00 <2.00> (+2.00)	⬇️
...oogle/cloud/spanner/PartitionedDmlTransaction.java	82.60% <83.33%> (+0.19%)	15.00 <0.00> (ø)
...ain/java/com/google/cloud/spanner/SessionPool.java	89.02% <91.17%> (+0.48%)	71.00 <0.00> (ø)
...ain/java/com/google/cloud/spanner/SessionImpl.java	85.79% <92.30%> (+1.77%)	30.00 <4.00> (+1.00)
...om/google/cloud/spanner/TransactionRunnerImpl.java	84.36% <93.75%> (+0.09%)	9.00 <0.00> (ø)
.../com/google/cloud/spanner/AbstractReadContext.java	86.76% <100.00%> (ø)	47.00 <0.00> (ø)
...gle/cloud/spanner/AsyncTransactionManagerImpl.java	71.83% <100.00%> (+0.40%)	12.00 <0.00> (ø)
...a/com/google/cloud/spanner/DatabaseClientImpl.java	84.46% <100.00%> (+3.51%)	21.00 <2.00> (+2.00)
...ud/spanner/SessionPoolAsyncTransactionManager.java	85.71% <100.00%> (+0.34%)	11.00 <0.00> (ø)
...m/google/cloud/spanner/TransactionManagerImpl.java	88.88% <100.00%> (+0.20%)	20.00 <1.00> (ø)
... and 1 more

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[thiagotnunes]

LGTM

[olavloite]

@skuruppu Do you want to weigh in on this as well? It is technically a (binary) breaking change as we are adding vararg arguments to a number of public interface methods. Existing client application code does not need to be changed, but it breaks binary compatibility, so it needs to be recompiled.

[skuruppu]

I think previously, we haven't marked changes that break binary compatibility as breaking changes so this is fine.