KZEC-5072, fix null upon agg. #90

Job	Run time
Error Prone (JDK 11)	3m 46s
Error Prone (JDK 11), Guava 31	3m 44s
Linux (JDK 11), Avatica main	6m 14s
CheckerFramework (JDK 11)	9m 2s
CheckerFramework (JDK 11), Guava 29	9m 11s
Druid Tests	6m 59s
Linux (JDK 11), Pacific/Chatham Timezone	7m 43s
Linux (JDK 17)	7m 43s
Linux (JDK 18)	7m 16s
Linux (JDK 8), Oldest Guava, America/New_York Timezone	8m 43s
Linux (JDK 8) Slow Tests	0s
macOS (JDK 18)	16m 22s
Windows (JDK 17)	11m 32s
Windows (JDK 8)	15m 25s
	1h 53m 40s

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