Array elements are assumed not to be nullable.

Array elements are assumed never to be nullable. We should set nullability based on the element values instead. https://github.com/apache/beam/blob/0c08687d902561f0cb0c1c51da512cebc4093d6e/sdks/java/extensions/sql/zetasql/src/main/java/org/apache/beam/sdk/extensions/sql/zetasql/ZetaSqlCalciteTranslationUtils.java#L293