Added unit test and refined implementation #252

Job	Run time
Windows (JDK 17)	14m 44s
Windows (JDK 8)	15m 59s
Linux (JDK 8), latest Guava, America/New_York Timezone	12m 17s
Linux (JDK 8), oldest Guava, America/New_York Timezone	11m 31s
Linux (JDK 11), Avatica main	14m 0s
Linux (JDK 11), Pacific/Chatham Timezone	10m 49s
Linux (JDK 17)	11m 19s
Linux (JDK 19)	9m 47s
Error Prone (JDK 11), latest Guava	4m 58s
CheckerFramework (JDK 11)	10m 33s
CheckerFramework (JDK 11), oldest Guava	10m 24s
Druid Tests	7m 18s
macOS (JDK 19)	37m 20s
Linux (JDK 8) Slow Tests	0s
	2h 50m 59s

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