fix typo for javadoc

[xaph]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/oblac/jodd/blob/master/CONTRIBUTING.md
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

Current behavior

New behavior?

[codecov]

Codecov Report

Merging #759 into master will increase coverage by 0.00%.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master     #759   +/-   ##
=========================================
  Coverage     66.90%   66.91%           
  Complexity    11709    11709           
=========================================
  Files           900      900           
  Lines         45580    45580           
  Branches       7345     7345           
=========================================
+ Hits          30496    30498    +2     
+ Misses        12690    12688    -2     
  Partials       2394     2394           

Impacted Files	Coverage Δ	Complexity Δ
jodd-json/src/main/java/jodd/json/JsonArray.java	87.50% <ø> (ø)	60.00 <0.00> (ø)
...jtx/src/main/java/jodd/jtx/JtxTransactionMode.java	62.06% <0.00%> (-3.45%)	8.00% <0.00%> (-1.00%)
jodd-core/src/main/java/jodd/io/StreamGobbler.java	64.28% <0.00%> (-2.39%)	4.00% <0.00%> (-1.00%)
...ore/src/main/java/jodd/cache/AbstractCacheMap.java	82.55% <0.00%> (+4.65%)	28.00% <0.00%> (+2.00%)

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[igr]

Thank you!!!!