Return null or something nullable from a lambda in transformation method

Reports transform operations that may return null inside a Reactive Stream chain.

Reactive Streams don't support nullable values, which causes such code to fail. The quick-fix suggests replacing map() with mapNotNull, which omits exceptions.

Example:

repository.findWithTailableCursorBy()
    .map(e -> (Person)null)
    .doOnNext(System.out::println)

After the quick-fix is applied:

repository.findWithTailableCursorBy()
    .mapNotNull(e -> (Person)null)
    .doOnNext(System.out::println)

Locating this inspection

By ID

Can be used to locate inspection in e.g. Qodana configuration files, where you can quickly enable or disable it, or adjust its settings.

ReactiveStreamsNullableInLambdaInTransform

Via Settings dialog

Path to the inspection settings via IntelliJ Platform IDE Settings dialog, when you need to adjust inspection settings directly from your IDE.

Settings or Preferences | Editor | Inspections | Reactive Streams | Common

New in 2019.3

Inspection Details
By default bundled with:	IntelliJ IDEA 2024.2, Qodana for JVM 2024.2,
Can be installed with plugin:	Reactive Streams, 242.22892

Last modified: 11 September 2024