How to use multiple appenders of same type with one logger using properties file? - log4j2

Question

I have what should be a simple question but I can't figure it out. What is the correct syntax to use multiple appenders of the same type (RollingFile) with a single logger in Log4j2 properties file format?
For background, I am using Karaf 4.2.7 which uses pax logging. My logging config file is in the properties format.
log4j2.appender.fileapp1.type = RollingRandomAccessFile
log4j2.appender.fileapp1.name = FileApp1
...
log4j2.appender.fileapp2.type = RollingRandomAccessFile
log4j2.appender.fileapp2.name = FileApp2
...
log4j2.logger.myloggername.name = com.acme
log4j2.logger.myloggername.appenderRef.RollingFile.ref = FileApp1, FileApp2
Putting both appenders on that last line separated by a comma does not work. It works if I have only one appender or the other. I also tried
log4j2.logger.myloggername.appenderRef.RollingFile.ref = [FileApp1, FileApp2]
log4j2.logger.myloggername.appenderRef.RollingFile.ref = {FileApp1, FileApp2}
log4j2.logger.myloggername.appenderRef.RollingFile.ref = [{FileApp1}, {FileApp2}]
None of those works. I can't seem to find any examples online of how to do this.

Answer 1

I refer to two web page(thanks).
log4j 2 log4j2.properties(Configuration option)
Log4J 2 Configuration: Using the Properties File
Add and define "~s".
appenders, appenderRefs,
This is notice for define what will be on next.
name=PropertiesConfig
property.filename_fileapp1 = ./logs/fileapp1.log
property.filename_fileapp2 = ./logs/fileapp2.log
appenders = console, fileapp1, fileapp2
appender.console.type = Console
appender.console.name = STDOUT
...
appender.fileapp1.type = RollingRandomAccessFile
appender.fileapp1.name = fileapp1_AppenderName
appender.fileapp1.fileName = ${filename_fileapp1}
appender.fileapp1.filePattern = ${filename_fileapp1}.%d{yyyy-MM-dd}.log
...
appender.fileapp2.type = RollingRandomAccessFile
appender.fileapp2.name = fileapp2_AppenderName
appender.fileapp2.fileName = ${filename_fileapp2}
appender.fileapp2.filePattern = ${filename_fileapp2}.%d{yyyy-MM-dd}.log
...
loggers = mylogger1
logger.mylogger1.name = com.jornathan.sample.log4j2PropertyTest
logger.mylogger1.level = info
#keep this value for testing.
logger.mylogger1.additivity = true
#Here is what you need.
logger.mylogger1.appenderRefs = fileapp1Appender, fileapp2Appender
logger.mylogger1.appenderRef.fileapp1Appender.ref = fileapp1_AppenderName
logger.mylogger1.appenderRef.fileapp2Appender.ref = fileapp2_AppenderName