Bump version of HdrHistogram to 2.1.9
<action issue="LOG4J2-1938" dev="ggregory" type="update">
Update Jackson from 2.8.7 to 2.8.9.
</action>
+ <action issue="LOG4J2-1970" dev="rpopma" type="update">
+ Update HdrHistogram from 2.1.8 to 2.1.9.
+ </action>
</release>
<release version="2.8.2" date="2017-04-02" description="GA Release 2.8.2">
<action issue="LOG4J2-1861" dev="mattsicker" type="fix">
