Method causeOrSelf

core/src/main/java/org/apache/calcite/util/Util.java:1108–1112

Returns cause of the given throwable if it is non-null or the throwable itself. @param throwable input throwable @return cause of the given throwable if it is non-null or the throwable itself

(Throwable throwable)

   * @return cause of the given throwable if it is non-null or the throwable itself
   */
  @API(since = "1.26", status = API.Status.EXPERIMENTAL)
  public static Throwable causeOrSelf(Throwable throwable) {
    Throwable cause = throwable.getCause();
    return cause != null ? cause : throwable;
  }

  /**
   * Retrieves messages in a exception and writes them to a string. In the