private static Cipher cipherInstance() throws GeneralSecurityException {
    return EngineFactory.CIPHER.getInstance("AES/GCM/NoPadding");
  }
Returns the expected size of the ciphertext for a given plaintext. The returned value includes
the header and offset.
java_src/src/main/java/com/google/crypto/tink/subtle/AesGcmHkdfStreaming.java