Add coder for java Enum

[jto]

No description provided.

[codecov]

Codecov Report

Merging #1434 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #1434      +/-   ##
==========================================
+ Coverage   79.06%   79.06%   +<.01%     
==========================================
  Files         161      161              
  Lines        5044     5045       +1     
  Branches      308      293      -15     
==========================================
+ Hits         3988     3989       +1     
  Misses       1056     1056

Impacted Files	Coverage Δ
...ain/scala/com/spotify/scio/coders/JavaCoders.scala	84.37% <100%> (+0.5%)	⬆️

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