message: Throw nullpointer exceptions if a KemKey is created without kemBytes or symmetricKey.
  I don't believe that anyone uses this differently, if they do, they will probably get a nullpointer exception elsewhere anyhow.
diff: @@ -28,7 +28,7 @@ import java.security.interfaces.ECPublicKey;
  * @since 1.0.0
  */
  public final class EciesHkdfSenderKem {
  - private ECPublicKey recipientPublicKey;
  + private final ECPublicKey recipientPublicKey;
  /** A container for key parts generated by the KEM. */
  public static final class KemKey {
  @@ -36,26 +36,24 @@ public final class EciesHkdfSenderKem {
  private final Bytes symmetricKey;
  public KemKey(final byte[] kemBytes, final byte[] symmetricKey) {
  + if (kemBytes == null) {
  + throw new NullPointerException("KemBytes must be non-null");
  + }
  + if (symmetricKey == null) {
  + throw new NullPointerException("symmetricKey must be non-null");
  + }
  this.kemBytes = Bytes.copyFrom(kemBytes);
  this.symmetricKey = Bytes.copyFrom(symmetricKey);
  }
  public byte[] getKemBytes() {
  - if (kemBytes == null) {
  - return null;
  - } else {
  return kemBytes.toByteArray();
  }
  - }
  public byte[] getSymmetricKey() {
  - if (symmetricKey == null) {
  - return null;
  - } else {
  return symmetricKey.toByteArray();
  }
  }
  - }
  public EciesHkdfSenderKem(final ECPublicKey recipientPublicKey) {
  this.recipientPublicKey = recipientPublicKey;
  