[LOG4J2-3458] LocalizedMessage logs misleading errors on the console

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.17.2
• Fix Version/s: 2.18.0
• Component/s: API
• Assignee: Unassigned
• Reporter: Gary D. Gregory
• Created: 30/Mar/22 23:01
• Updated: 02/May/22 21:12
• Resolved: 31/Mar/22 04:37

Description

I have an app where we log data that is percent encoded through a localized message factory. We get a ton of noise on the console due to logging of internal exceptions, for example:

ERROR StatusLogger Unable to format msg: C:/Program%20Files/Some%20Company/Some%20Product%20Name/
 java.util.UnknownFormatConversionException: Conversion = 'F'
    at java.util.Formatter$FormatSpecifier.conversion(Formatter.java:2691)
    at java.util.Formatter$FormatSpecifier.<init>(Formatter.java:2720)
    at java.util.Formatter.parse(Formatter.java:2560)
    at java.util.Formatter.format(Formatter.java:2501)
    at java.util.Formatter.format(Formatter.java:2455)
    at java.lang.String.format(String.java:2981)
    at org.apache.logging.log4j.message.StringFormattedMessage.formatMessage(StringFormattedMessage.java:116)
    at org.apache.logging.log4j.message.StringFormattedMessage.getFormattedMessage(StringFormattedMessage.java:88)
    at org.apache.logging.log4j.message.FormattedMessage.getFormattedMessage(FormattedMessage.java:178)
    at org.apache.logging.log4j.message.LocalizedMessage.getFormattedMessage(LocalizedMessage.java:196)
    at org.apache.logging.log4j.message.LocalizedSimpleMessageFactoryTest.testNoMatchPercentInMessage(LocalizedSimpleMessageFactoryTest.java:79)

I updated this test to demonstrate: https://github.com/apache/logging-log4j2/blob/release-2.x/log4j-api/src/test/java/org/apache/logging/log4j/message/LocalizedMessageFactoryTest.java

In a nutshell:

    @Test
    public void testNoMatchPercentInMessage() {
        final LocalizedMessageFactory localizedMessageFactory = new LocalizedMessageFactory(ResourceBundle.getBundle("MF", Locale.US));
        final Message message = localizedMessageFactory.newMessage("C:/Program%20Files/Some%20Company/Some%20Product%20Name/");
        assertEquals("C:/Program%20Files/Some%20Company/Some%20Product%20Name/", message.getFormattedMessage());
    }

Options:

• Don't log the exception (simple)
• Log at the TRACE level instead of ERROR.
• Provide a better simpler localized MessageFactory that does not perform % substitution
• ?

I read the Javadoc that says that using a localized MessageFactory is not preferred, but it would be a large change for our app.