Merge branch 'refactor' of https://github.com/polypheny/Polypheny-DB … #3598

Job	Run time
Integration Tests (Java 11) (mongodb)	1h 39m 47s
Integration Tests (Java 11) (hsqldb)	1h 21m 29s
Integration Tests (Java 11) (monetdb)	26m 36s
Integration Tests (Java 11) (postgresql)	1h 38m 44s
Integration Tests (Java 11) (file)	15m 44s
Integration Tests (Java 11) (cottontail)	1h 39m 46s
Integration Tests (Java 11) (cassandra)	9m 53s
Integration Tests (Java 11) (neo4j)	1h 40m 56s
	8h 52m 55s

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