When using a protected constructor 
javax.crypto.Cipher���(CipherSpi, Provider, String)
and running a standalone sample implementation an NPE could be thrown which is not specified anyhow.

Exception in thread "main" java.lang.NullPointerException
	at java.base/javax.crypto.Cipher.<init>(Cipher.java:279)
	at TestCipherSpi$MyCipher.<init>(TestCipherSpi.java:23)
	at TestCipherSpi.main(TestCipherSpi.java:28)

===================
....
    static class MyCipher extends Cipher {
        protected MyCipher(javax.crypto.CipherSpi cipherSpi, Provider provider, String transformation) {
            super(cipherSpi, provider, transformation);
        }
    }
    
    public static void main(String[] args) throws Exception {
        Cipher cipher = new MyCipher(mockedCipherSpi, new Provider("a", "b", "c") {
            @Override
            public Provider configure(String configArg) {
                return super.configure(configArg);
            }
        }, "abc");        
    }
    
    static CipherSpi mockedCipherSpi = new CipherSpi() {
   ...
===================


Please see the attached full code sample to reproduce the problem.