Why is this an issue?

A long parameter list can indicate that a new structure should be created to wrap the numerous parameters or that the function is doing too many things.

Noncompliant code example

With a maximum number of 4 parameters:

public function addData(p1 : int, p2 : int, p3 : int, p4 : int, p5 : int): void  {
...
}

Compliant solution

public function addData(p1 : int, p2 : int, p3 : int, p4 : int): void  {
...
}