Align Hazelcast UC3 implementation with others

...ocks/theodolite/benchmarks/uc2/beam/StatsAggregation.java

...nchmarks/uc2/hazelcastjet/StatsAccumulatorSerializer.java

...benchmarks/uc2/hazelcastjet/StatsAccumulatorSupplier.java

...e/benchmarks/uc2/hazelcastjet/StatsAggregatorFactory.java

...ocks/theodolite/benchmarks/uc3/beam/StatsAggregation.java

...heodolite/benchmarks/uc3/hazelcastjet/HistoryService.java

...nchmarks/uc3/hazelcastjet/StatsAccumulatorSerializer.java

...benchmarks/uc3/hazelcastjet/StatsAccumulatorSupplier.java

...e/benchmarks/uc3/hazelcastjet/StatsAggregatorFactory.java

...olite/benchmarks/uc3/hazelcastjet/Uc3PipelineFactory.java

...eodolite/benchmarks/uc3/hazelcastjet/Uc3PipelineTest.java