@Override
  public byte[] labeledExtract(byte[] salt, byte[] ikm, String ikmLabel, byte[] suiteId)
      throws GeneralSecurityException {
    return extract(HpkeUtil.labelIkm(ikmLabel, ikm, suiteId), salt);
  }
Copied from {@link com.google.crypto.tink.subtle.Hkdf#computeHkdf(String, byte[], byte[],
byte[], int)}
java_src/src/main/java/com/google/crypto/tink/hybrid/internal/HkdfHpkeKdf.java