Code Inspection for unnecessary 'Optional.flatMap()'

Clean Code New rules / language support
1

Type: Code Smell

The following Code snippets makes use of an unnecessary ‘Optional.flatMap()’ call. There should never be a reason to manually wrap a mapping operation into a Optional type.

Noncompliant Code:

// (1)
Optional.of(2)
        .flatMap(value -> Optional.of(1));

// (2)
Optional.ofNullable(2)
        .flatMap(value -> Optional.ofNullable(1));

Compliant Code:

// (1)
Optional.of(2)
        .map(value -> 1);

// (2) 
Optional.ofNullable(2)
        .map(value -> 1);

Note that in case of (1) the compliant code actually changes the behaviour since Optional.of() would throw an exception if a null value is provided, while Optional.map() would return an empty Optional. Therefore it might require more user-interaction.
Case (2) should be always compliant.

Also see the following request on IntelliJ IDEA:
https://youtrack.jetbrains.com/issue/IDEA-236581/Inspection-to-simplify-Optional.flatMap