It's not possible to fix P13 when null is returning from external library

[g4s8]

We can't avoid nulls returning from Java classes or third-party dependency, e.g. String prop = System.getProperty("name") so we need to check it for nulls, so the pattern P13 doesn't make sense in this case. I'd keep only P16 (return null).

[lyriccoder]

@yegor256 comment pls