https://docs.oracle.com/en/java/javase/19/docs/api/java.prefs/java/util/prefs/AbstractPreferences.html#remove(java.lang.String)

the above is rendered as:

Throws:
IllegalStateException - if this node (or an ancestor) has been removed with the removeNode() method.
IllegalArgumentException - if key contains the null control character, code point U+0000.
NullPointerException - if key is null..

(Note two successive periods after null in the NPE entry). That happens because of this:

     * @throws NullPointerException {@inheritDoc}.
     */
    public void remove(String key) {

     ...

     * @throws NullPointerException if {@code key} is {@code null}.
     ...
     */
    public abstract void remove(String key);