Why is this an issue?
Specifying the default parameter values in a method call is redundant. Such values should be omitted in the interests of readability.
Noncompliant code example
public void M(int x, int y=5, int z = 7) { /* ... */ }
// ...
M(1, 5); // Noncompliant, y has the default value
M(1, z: 7); // Noncompliant, z has the default value
Compliant solution
public void M(int x, int y=5, int z = 7) { /* ... */ }
// ...
M(1);
M(1);