fix: deprecate Blob.update() and modify documentation of Storage.update methods

[dmitry-fa]

Fixes #234

[codecov]

Codecov Report

Merging #236 into master will not change coverage by %.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master     #236   +/-   ##
=========================================
  Coverage     63.50%   63.50%           
  Complexity      540      540           
=========================================
  Files            30       30           
  Lines          4762     4762           
  Branches        427      427           
=========================================
  Hits           3024     3024           
  Misses         1578     1578           
  Partials        160      160           

Impacted Files	Coverage Δ	Complexity Δ
...e/src/main/java/com/google/cloud/storage/Blob.java	81.97% <ø> (ø)	29.00 <0.00> (ø)
...rc/main/java/com/google/cloud/storage/Storage.java	80.57% <ø> (ø)	0.00 <0.00> (ø)

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[frankyn]

Please wait to merge this until I have a chance to review next week.

[dmitry-fa]

@frankyn

Please wait to merge this until I have a chance to review next week.

Sure!

Please note, the doc has been updated to be aligned with
#233

[frankyn]

Updated, please don't deprecate this method. It's a reasonable convenience method. I added an example in the associated issue.

Users may be dependent on this method and deprecating it can cause friction as we've seen before with the deprecation of Storage.create() for InputStream.