avoid_types_on_closure_parameters

Unnecessary type annotation on a function expression parameter.

The analyzer produces this diagnostic when a parameter of a function expression (closure) has an explicit type annotation, and the closure is in a context where the parameter type can be inferred.

The following code produces this diagnostic because the parameter x in the closure passed to l.map has an explicit type annotation of int, which is unnecessary because the type can be inferred from the list's type:

void f(List<int> l) {
  l.map((int x) => x.isEven);
}

Remove the type annotation:

void f(List<int> l) {
  l.map((x) => x.isEven);
}