adjusted toString to allow correct pushdown of operation of jdbc #3586

Job	Run time
Integration Tests (Java 11) (mongodb)	1h 16m 20s
Integration Tests (Java 11) (hsqldb)	18m 41s
Integration Tests (Java 11) (monetdb)	14m 6s
Integration Tests (Java 11) (postgresql)	1h 15m 36s
Integration Tests (Java 11) (file)	14m 51s
Integration Tests (Java 11) (cottontail)	16m 49s
Integration Tests (Java 11) (cassandra)	11m 9s
Integration Tests (Java 11) (neo4j)	1h 38m 43s
	5h 26m 15s

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