Bug in AdditionalPropertiesFalseValidator

[Stranger6667]

There is no test case for it, but instead of :

fn is_valid(&self, _: &JSONSchema, instance: &Value) -> bool {
        if let Value::Object(item) = instance {
            return item.iter().next().is_some();
        }
        true
    }

it should be:

fn is_valid(&self, _: &JSONSchema, instance: &Value) -> bool {
        if let Value::Object(item) = instance {
            return item.iter().next().is_none();
        }
        true
    }

I.e. it is only valid on objects without properties