Chains of safe calls on non-nullable types are redundant and can be removed by enclosing the redundant safe calls in a run {} block. This improves code coverage and reduces cyclomatic complexity as redundant null checks are removed. This rule only checks from the end of a chain and works backwards, so it won't recommend inserting run blocks in the middle of a safe call chain as that is likely to make the code more difficult to understand. The rule will check for every opportunity to replace a safe call when it sits at the end of a chain, even if there's only one, as that will still improve code coverage and reduce cyclomatic complexity.

Noncompliant Code

val x = System.getenv()
?.getValue("HOME")
?.toLowerCase()
?.split("/") ?: emptyList()

Compliant Code

val x = getenv()?.run {
getValue("HOME")
.toLowerCase()
.split("/")
} ?: emptyList()