The spec for javax.crypto.Mac.update(ByteBuffer input) method said:
"
Processes input.remaining() bytes in the ByteBuffer input, starting at input.position(). Upon return, the buffer's position will be equal to its limit; its limit will not have changed.

Parameters:
    input - the ByteBuffer
Throws:
    IllegalStateException - if this Mac has not been initialized.
"

Nothing said about what happens if the input is null.

In that time the IllegalArgumentException will be thrown if pass null pointer:

public class MacUpdate {
    public static void main(String[] args) {
        try {
            //Generate secret key
            KeyGenerator kg = KeyGenerator.getInstance("HmacSHA1");
            SecretKey key = kg.generateKey();
        
            //Instantiate Mac
            Mac theMac = Mac.getInstance("HmacSHA1");
            theMac.init(key);
            
            //do test
            ByteBuffer buf = null;
            theMac.update(buf);
            theMac.doFinal();
        } catch(IllegalArgumentException e){
            System.out.println(e.toString());//we shouldn'g be here according to spec.
        } catch (Exception e){
            e.printStackTrace();
        }
    }
}

The output will be
java.lang.IllegalArgumentException: Buffer must not be null

I guess the spec need to be updated (at least for JDK8).