fix: increase visibility of #get()

[olavloite]

Increases the visibility of AbstractLazyInitializer#get() to make it usable outside the client library.

Replaces #461.

[codecov]

Codecov Report

Merging #486 into master will increase coverage by 0.00%.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master     #486   +/-   ##
=========================================
  Coverage     82.20%   82.20%           
- Complexity     2466     2469    +3     
=========================================
  Files           138      138           
  Lines         13631    13631           
  Branches       1312     1312           
=========================================
+ Hits          11205    11206    +1     
  Misses         1896     1896           
+ Partials        530      529    -1     

Impacted Files	Coverage Δ	Complexity Δ
.../google/cloud/spanner/AbstractLazyInitializer.java	100.00% <ø> (+7.14%)	5.00 <0.00> (+1.00)

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[thiagotnunes]

LGTM, do we have to cut a major for this? @olavloite

[olavloite]

LGTM, do we have to cut a major for this? @olavloite

I would say no. This only adds visibility, so it should not break anything for anyone.

I would also like to reduce the visibility of the initialize method to protected, which would be a breaking change, but I would prefer to include that change with other breaking changes instead of having to cut a major release just for that.