@Override
  public String toString() {
    StringBuilder sb = new StringBuilder();
    sb.append(getResult());
    sb.append(lineSeparator());
    if (getStackTrace() != null) {
      sb.append(getStackTrace());
    }
    return sb.toString();
  }
This constructor is invoked when invoking a method resulted in an exception being thrown. The
"result" is set to {@link #EXCEPTION_OCCURRED}. If the exception could not be serialized,
{@link #getException()} will return IOException with the exception stack as the message.
geode-dunit/src/main/java/org/apache/geode/test/dunit/internal/MethodInvokerResult.java