Given the following code:

void f({@deprecated required int c}) {}
void g() {
  f(c: 2);
}

The analyzer marks the argument named c as being deprecated claiming that it shouldn't be used, but the call site is required to provide a value. There's no way for the user to fix the diagnostic, so we probably shouldn't produce it.

On the other hand, we should probably have a diagnostic indicating that it doesn't make sense to have a parameter that's both deprecated and required and suggest that users remove required and either make the parameter nullable or provide a default value.