Cannot suppress `AddNullMarkedToClass`, `AddNullMarkedToPackageInfo`

In Error Prone 2.45.0 through 2.48.0 the following suppressions have no effect:

```java
@SuppressWarnings("AddNullMarkedToPackageInfo")
package foo;
```

```java
@SuppressWarnings("AddNullMarkedToClass")
public class Foo {}
```

Other known-good suppressions work as usual, including `VoidMissingNullable` whether on method or class level. I assume, but did not verify, that the former has never worked.

If this curiosity is fine then documentation should probably suppress the suppression section. I only discovered this because I was constructing a synthetic example to check nullness analysis configuration.