$ java -cp classes ApiTour      (25.0.5+8-LTS)
== KDF algorithms registered by the providers of this JDK
SunJCE  HKDF-SHA256
SunJCE  HKDF-SHA384
SunJCE  HKDF-SHA512
== getInstance: what works and what does not
algorithm=HKDF-SHA256 provider=SunJCE parameters=null
HKDF -> NoSuchAlgorithmException: No available provider supports the specified algorithm
HKDF-SHA1 -> NoSuchAlgorithmException: No available provider supports the specified algorithm
hkdf-sha256 -> available
PBKDF2WithHmacSHA256 -> NoSuchAlgorithmException: No available provider supports the specified algorithm
Argon2 -> NoSuchAlgorithmException: No available provider supports the specified algorithm
== Shape 1: extract then expand in one call (the common case)
deriveData  -> byte[42] 3cb25f25faacd57a90434f64d0362f2a2d2d0a90cf1a5a4c5db02d56ecc4c5bf34007208d5b887185865
deriveKey   -> algorithm=AES format=RAW bytes=32
== Shape 2: extract only (returns the pseudorandom key, PRK)
PRK = 077709362c2e32df0ddc3f0dc47bba6390b6c73bb50f9c3122ec844ad7c2b3e5
== Shape 3: expand only (you already hold a uniformly random key)
PASS  extractOnly + expandOnly equals the one-call result
== The same KDF object can be used again, and gives the same bytes
PASS  second call with the same spec is identical
== Several IKM or salt pieces are concatenated in the order added
PASS  addIKM(first 10) + addIKM(last 12) == addIKM(all 22)
== deriveKey does not check key sizes; Cipher.init does
deriveKey("AES") length 16 -> ok, 16 bytes
                   Cipher.init -> ok
deriveKey("AES") length 24 -> ok, 24 bytes
                   Cipher.init -> ok
deriveKey("AES") length 32 -> ok, 32 bytes
                   Cipher.init -> ok
deriveKey("AES") length 20 -> ok, 20 bytes
                   Cipher.init -> InvalidKeyException: Invalid AES key length: 20 bytes
ALL CHECKS PASSED
exit=0