@CanIgnoreReturnValue
    public Builder setPublicKey(JwtRsaSsaPkcs1PublicKey publicKey) {
      this.publicKey = Optional.of(publicKey);
      return this;
    }
Sets the public key, which includes the parameters.

<p>This is required.
java_src/src/main/java/com/google/crypto/tink/jwt/JwtRsaSsaPkcs1PrivateKey.java