System logger and unexpanded placeholders

[Travis Spencer]

Hi All,

I just learned about the Log4j JDK Platform Logging Adapter. I added
log4j-jpl-2.17.1.jar to my class path.

I added this to my log4j config file:

<Logger name="java.io.serialization" level="TRACE" />

Now, I see this in my log file:

2022-01-04T15:05:52:849+0100 TRACE 8P1u2Wr5 dd4ec2e6 {req-169}
java.io.serialization:-1 ObjectInputFilter {0}: {1}, array length: {2},
nRefs: {3}, depth: {4}, bytes: {5}, ex: {6}

Looking at the OpenJDK 11 code at
java.base/java/io/ObjectInputStream.java:1345, I see this:

Logging.filterLogger.log(status == null || status ==
ObjectInputFilter.Status.REJECTED
                                ? Logger.Level.DEBUG
                                : Logger.Level.TRACE,
                        "ObjectInputFilter {0}: {1}, array length: {2},
nRefs: {3}, depth: {4}, bytes: {5}, ex: {6}",
                        status, clazz, arrayLength, totalObjectRefs, depth,
bytesRead,
                        Objects.toString(ex, "n/a"));

This logger seems to be set above this on line 300ish:

static {
            Logger filterLog = System.getLogger("java.io.serialization");
            filterLogger = (filterLog.isLoggable(Logger.Level.DEBUG)
                    || filterLog.isLoggable(Logger.Level.TRACE)) ?
filterLog : null;
        }

So, the placeholders don't seem to get changed for their parameter values.
Do I need to do something more in the Log4j JDK Platform Logging Adapter to
make this work or is this perhaps a bug?

TIA!

--

Regards,

Travis Spencer