ARROW-5063: [Java] Followup to fix compilation for TestFlightClient

[BryanCutler]

This fixes a compilation issue that was missed in CI after #4282 was merged.

[BryanCutler]

Closing in favor of #4713

[codecov-io]

Codecov Report

Merging #4714 into master will increase coverage by 6.46%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #4714      +/-   ##
==========================================
+ Coverage   82.97%   89.44%   +6.46%     
==========================================
  Files         248      658     +410     
  Lines       18838    94718   +75880     
  Branches     1418        0    -1418     
==========================================
+ Hits        15630    84716   +69086     
- Misses       2846    10002    +7156     
+ Partials      362        0     -362

Impacted Files	Coverage Δ
r/src/recordbatch.cpp
r/R/Table.R
js/src/util/fn.ts
r/src/symbols.cpp
r/R/Column.R
go/arrow/ipc/file_reader.go
js/src/builder/index.ts
r/src/arrow_types.h
js/src/enum.ts
r/src/array_from_vector.cpp
... and 896 more

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