// Test nested exception handling
        Exception level3 = new RuntimeException("Level 3 error");
        Exception level2 = new IllegalStateException("Level 2 error", level3);
        Exception level1 = new IOException("Level 1 error", level2);
        SsoLoginException exception = new SsoLoginException("Top level SSO error", level1);

        assertEquals("Top level SSO error", exception.getMessage());

    if (bubbledTo == vacated) {
      // Could not bubble toTrickle up min levels, try moving
      // it from min level to max level (or max to min level) and bubble up
      // there.
      return heap.tryCrossOverAndBubbleUp(index, vacated, toTrickle);
    } else {
      return (bubbledTo < index) ? new MoveDesc<E>(toTrickle, elementData(index)) : null;
    }
  }

    if (bubbledTo == vacated) {
      // Could not bubble toTrickle up min levels, try moving
      // it from min level to max level (or max to min level) and bubble up
      // there.
      return heap.tryCrossOverAndBubbleUp(index, vacated, toTrickle);
    } else {
      return (bubbledTo < index) ? new MoveDesc<E>(toTrickle, elementData(index)) : null;
    }
  }

 *       <ul>
 *         <li>2 levels: average of 64ns per lock()/unlock()
 *         <li>3 levels: average of 77ns per lock()/unlock()
 *         <li>4 levels: average of 99ns per lock()/unlock()
 *         <li>5 levels: average of 103ns per lock()/unlock()
 *         <li>10 levels: average of 184ns per lock()/unlock()
 *         <li>20 levels: average of 393ns per lock()/unlock()
 *       </ul>
 * </ul>

                .setLevel(Level.ERROR)
                .setMessage(new SimpleMessage("test message 3"))
                .build();

        LogEvent result1 = policy.rewrite(event1);
        LogEvent result2 = policy.rewrite(event2);
        LogEvent result3 = policy.rewrite(event3);

        assertEquals(Level.WARN, result1.getLevel());
        assertEquals(Level.WARN, result2.getLevel());

		<Logger name="org.lastaflute" additivity="false" level="${log.level}">
			<AppenderRef ref="AppFile" />
			<AppenderRef ref="LogNotification" />
		</Logger>
		<Logger name="org.opensearch.bootstrap" additivity="false" level="error">
			<AppenderRef ref="AppFile" />
		</Logger>
		<Logger name="com.onelogin.saml2" level="off"/>
		<Logger name="org.codelibs.fess.llm" additivity="false" level="${llm.log.level}">
			<AppenderRef ref="LlmFile" />

		<LogNotificationAppender name="LogNotification"
			minLevel="${sys:fess.log.notification.level:-ERROR}" />
	</Appenders>

	<Loggers>
		<Logger name="org.codelibs.fess" additivity="false" level="${log.level}">
			<AppenderRef ref="AppFile" />
			<AppenderRef ref="LogNotification" />
		</Logger>
		<Root level="${root.log.level}">
			<AppenderRef ref="AppFile" />
			<AppenderRef ref="LogNotification" />
		</Root>
	</Loggers>

		<LogNotificationAppender name="LogNotification"
			minLevel="${sys:fess.log.notification.level:-ERROR}" />
	</Appenders>

	<Loggers>
		<Logger name="org.codelibs.fess" additivity="false" level="${log.level}">
			<AppenderRef ref="AppFile" />
			<AppenderRef ref="LogNotification" />
		</Logger>
		<Root level="${root.log.level}">
			<AppenderRef ref="AppFile" />
			<AppenderRef ref="LogNotification" />
		</Root>
	</Loggers>

        if (name == null) {
            LOGGER.error("No name provided for LogNotificationAppender");
            return null;
        }
        final Level level = Level.toLevel(minLevel, Level.ERROR);
        return new LogNotificationAppender(name, filter, layout, true, Property.EMPTY_ARRAY, level);
    }

    /**
     * Set the value of level, used in parameter comment. <br>
     * Even if empty string, treated as empty plainly. So "IF pmb != null" is false if empty.
     * @param level The parameter value of level. (NotNull)
     */
    public void setLevel(String level) {
        registerVariable("level", level);
    }

    /**