@RestrictedApi(
      explanation = "Accessing parts of keys can produce unexpected incompatibilities, annotate the function with @AccessesPartialKey",
      link = "https://developers.google.com/tink/design/access_control#accessing_partial_keys",
      allowedOnPath = ".*Test\\.java",
      allowlistAnnotations = {AccessesPartialKey.class})
  @Nullable
  public SecretBigInteger getNistPrivateKeyValue() {
    return nistPrivateKeyValue;
  }
Creates a new ECIES private key using NIST Curves.

@param publicKey Corresponding ECIES public key for this private key
@param nistPrivateKeyValue private big integer value in bigendian representation
java_src/src/main/java/com/google/crypto/tink/hybrid/EciesPrivateKey.java