I have the following example configuration:

<property name="Layout1" value="[Layout1] "xyz""/>

<appender name="LayoutTest_Console" class="ch.qos.logback.core.ConsoleAppender">
<filter class="ch.qos.logback.classic.filter.ThresholdFilter">
<level>TRACE</level>
</filter>
<layout class="ch.qos.logback.classic.PatternLayout">
<Pattern>
[%date

{yyyy-MM-dd HH:mm:ss.SSS}

] ${Layout1} [Layout2] "xyz"%n
</Pattern>
</layout>
</appender>

and this produces the following output:

[2010-01-05 13:06:34.897] [Layout1] "xyz" [Layout2]"xyz"

Notice the missing space between [Layout2] and "xyz" in the output that was present in the configuration.

The investigation shows a bug in ch.qos.logback.core.joran.event.SaxEventRecorder:
public void characters(char[] ch, int start, int length) {

String body = new String(ch, start, length);
if (body == null)

{ return; }

// if the body string is null
if (body != null) {
String bodyTrimmed = body.trim();
if (bodyTrimmed.length() == 0)

{ return; }
}

SaxEvent lastEvent = getLastEvent();
if (lastEvent instanceof BodyEvent) { BodyEvent be = (BodyEvent) lastEvent; be.append(body); } else { saxEventList.add(new BodyEvent(body, getLocator())); }

}

In my case the following calls were made to this method:
1. "[%date{yyyy-MM-dd HH:mm:ss.SSS}] ${Layout1} [Layout2]"
2. " "
3. """
4. "xyz"
5. """
6. "%n".

Note that the calls actually performed depend on the actual body content within the file and the actually used SAX parser (in my case com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl$JAXPSAXParser).

So within the method the:
// if the body string is null
if (body != null) {
String bodyTrimmed = body.trim();
if (bodyTrimmed.length() == 0) { return; }

}
must not occur if the last event was already a BodyEvent.