void should not have the same behavior as dynamic

[hgraceb]

Description

• When using <Null>, it prompts Unnecessary use of the type 'Null'. and suggests Try using 'void' instead.
• After changing <Null> to <void>, the behavior completely changed.

Example

https://dartpad.dev/33706e19df021e52d98c?id=2a911d811fe62681110cd69734328c22

class Class<T> {
  isNull() => null is T;

  isBool() => true is T;

  isString() => '' is T;

  isNever() => Never is T;
}

void main() {
  print('Class<Null>().isNull(): ${Class<Null>().isNull()}');           // true
  print('Class<Null>().isBool(): ${Class<Null>().isBool()}');           // false
  print('Class<Null>().isString(): ${Class<Null>().isString()}');       // false
  print('Class<Null>().isNever(): ${Class<Null>().isNever()}');         // false

  print('Class<void>().isNull(): ${Class<void>().isNull()}');           // true
  print('Class<void>().isBool(): ${Class<void>().isBool()}');           // true
  print('Class<void>().isString(): ${Class<void>().isString()}');       // true
  print('Class<void>().isNever(): ${Class<void>().isNever()}');         // true

  print('Class<String>().isNull(): ${Class<String>().isNull()}');       // false
  print('Class<String>().isBool(): ${Class<String>().isBool()}');       // false
  print('Class<String>().isString(): ${Class<String>().isString()}');   // true
  print('Class<String>().isNever(): ${Class<String>().isNever()}');     // false

  print('Class<dynamic>().isNull(): ${Class<dynamic>().isNull()}');     // true
  print('Class<dynamic>().isBool(): ${Class<dynamic>().isBool()}');     // true
  print('Class<dynamic>().isString(): ${Class<dynamic>().isString()}'); // true
  print('Class<dynamic>().isNever(): ${Class<dynamic>().isNever()}');   // true
}

Expected

• There is no suggestion to change <Null> to <void>.
• Modify the behavior of <void> if necessary.

[lrhn]

The behavior of void is correct, it's a supertype of any type, which is why any type can be assigned to it.

The warning is the issue.
It's a known issue that the "prefer void to null" lint has false positives, and might have outlived its usefulness: #59309