We found two problems in the implementation that was done to support tuples on native query.

Related to:
https://hibernate.atlassian.net/browse/HHH-11176
https://github.com/hibernate/hibernate-orm/pull/1955

Problem 1: It does not work with the stream method, as the following example:
em.createNativeQuery("select 1 as one, 2 as two", Tuple.class).stream().forEach(...);

Stack Trace:
org.hibernate.HibernateException: Got different size of tuples and aliases
at org.hibernate.jpa.spi.NativeQueryTupleTransformer$NativeTupleImpl.<init>(NativeQueryTupleTransformer.java:55) ~[hibernate-core-5.2.11-SNAPSHOT.jar:5.2.11.SNAPSHOT]
at org.hibernate.jpa.spi.NativeQueryTupleTransformer.transformTuple(NativeQueryTupleTransformer.java:22) ~[hibernate-core-5.2.11-SNAPSHOT.jar:5.2.11.SNAPSHOT]
at org.hibernate.hql.internal.HolderInstantiator.instantiate(HolderInstantiator.java:75) ~[hibernate-core-5.2.11-SNAPSHOT.jar:5.2.11.SNAPSHOT]
at org.hibernate.internal.ScrollableResultsImpl.prepareCurrentRow(ScrollableResultsImpl.java:206) ~[hibernate-core-5.2.11-SNAPSHOT.jar:5.2.11.SNAPSHOT]
at org.hibernate.internal.ScrollableResultsImpl.next(ScrollableResultsImpl.java:100) ~[hibernate-core-5.2.11-SNAPSHOT.jar:5.2.11.SNAPSHOT]
at org.hibernate.query.internal.ScrollableResultsIterator.hasNext(ScrollableResultsIterator.java:33) ~[hibernate-core-5.2.11-SNAPSHOT.jar:5.2.11.SNAPSHOT]
at java.util.Iterator.forEachRemaining(Iterator.java:115) ~[na:1.8.0_131]
at java.util.Spliterators$IteratorSpliterator.forEachRemaining(Spliterators.java:1801) ~[na:1.8.0_131]
at java.util.stream.ReferencePipeline$Head.forEach(ReferencePipeline.java:580) ~[na:1.8.0_131]

Problem 2: It breaks if the first row contain null values.

If the first row contains null values, it breaks (due to the getClass - https://github.com/galovics/hibernate-orm/blob/090ab4646ad1926f378e3f1608ffe900758b07d2/hibernate-core/src/main/java/org/hibernate/jpa/spi/NativeQueryTupleTransformer.java#L121 )

Stack Trace:
java.lang.NullPointerException: null
at org.hibernate.jpa.spi.NativeQueryTupleTransformer$NativeTupleImpl.getElements(NativeQueryTupleTransformer.java:109) ~[hibernate-core-5.2.11-SNAPSHOT.jar:5.2.11.SNAPSHOT]