message: Populate message in NullpointerException.
diff: @@ -27,7 +27,7 @@ public final class TinkProtoKeysetFormat {
  public static KeysetHandle parseKeyset(byte[] serializedKeyset, SecretKeyAccess access)
  throws GeneralSecurityException {
  if (access == null) {
  - throw new NullPointerException("...");
  + throw new NullPointerException("SecretKeyAccess cannot be null");
  }
  SecretKeyAccess.requireAccess(access);
  try {
  @@ -41,7 +41,7 @@ public final class TinkProtoKeysetFormat {
  public static byte[] serializeKeyset(KeysetHandle keysetHandle, SecretKeyAccess access)
  throws GeneralSecurityException {
  if (access == null) {
  - throw new NullPointerException("...");
  + throw new NullPointerException("SecretKeyAccess cannot be null");
  }
  SecretKeyAccess.requireAccess(access);
  try {
  