[STORM-3944] Synchronize access to map in Multi*Metric #184

Job	Run time
build (ubuntu-latest, 11, Client, false)	10m 22s
build (ubuntu-latest, 11, Server, false)	26m 3s
build (ubuntu-latest, 11, Core, false)	16m 49s
build (ubuntu-latest, 11, External, false)	16m 13s
build (ubuntu-latest, 11, Check-Updated-License-Files, false)	17m 41s
build (ubuntu-latest, 11, Integration-Test, false)	12m 58s
build (ubuntu-latest, 17, Client, false)	26m 40s
build (ubuntu-latest, 17, Server, false)	40m 56s
build (ubuntu-latest, 17, Core, false)	14m 40s
build (ubuntu-latest, 17, External, false)	20m 19s
build (ubuntu-latest, 17, Check-Updated-License-Files, false)	15m 37s
build (ubuntu-latest, 17, Integration-Test, false)	12m 47s
	3h 51m 5s

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