Why is this an issue?

Jump statements (return, break and continue) move control flow out of the current code block. So any statements that come after a jump are dead code.

Noncompliant code example

fun foo(a: Int): Int {
  var i = 10;
  return a + i;       // Noncompliant
  i++;                // dead code
}

Compliant solution

fun foo(a: Int): Int {
  var i = 10;
  return a + i;
}

Resources