NPE in logback-core on startup if given invalid file.encoding

[kriss-s]

If one sets file.encoding to an unsupported encoding string (for example ISO-8859 missing the last qualifier ISO-8859-1) logback fails to start with an unhelpful java.lang.NullPointerException.

The encoding exception is swallowed in the deprecated URLDecoder.decode(String) used below in logback-core.

https://github.com/qos-ch/logback/blob/9078f68f49673d2163ebbaa075ec4018a6d12e54/logback-core/src/main/java/ch/qos/logback/core/joran/spi/ConfigurationWatchList.java#L97C40-L97C46

There is a fix in openjdk 22+18 that would resolve this however, but it's a bit nasty untill one can update. So for all java (8, 22+17] there is this NPE.

https://bugs.openjdk.org/browse/JDK-8317246

Failed to instantiate [ch.qos.logback.classic.LoggerContext]
Reported exception:
java.lang.NullPointerException
     at java.base/java.io.File.<init>(File.java:278)
     at ch.qos.logback.core.joran.spi.ConfigurationWatchList.convertToFile(ConfigurationWatchList.java:95)
     at ch.qos.logback.core.joran.spi.ConfigurationWatchList.addAsFileToWatch(ConfigurationWatchList.java:59)
     at ch.qos.logback.core.joran.spi.ConfigurationWatchList.setMainURL(ConfigurationWatchList.java:55)
     at ch.qos.logback.core.joran.util.ConfigurationWatchListUtil.setMainWatchURL(ConfigurationWatchListUtil.java:50)
     at ch.qos.logback.core.joran.GenericConfigurator.informContextOfURLUsedForConfiguration(GenericConfigurator.java:100)
     at ch.qos.logback.core.joran.GenericConfigurator.doConfigure(GenericConfigurator.java:46)
     at ch.qos.logback.classic.util.ContextInitializer.configureByResource(ContextInitializer.java:75)
     at ch.qos.logback.classic.util.ContextInitializer.autoConfig(ContextInitializer.java:150)
     at org.slf4j.impl.StaticLoggerBinder.init(StaticLoggerBinder.java:84)
     at org.slf4j.impl.StaticLoggerBinder.<clinit>(StaticLoggerBinder.java:55)
     at org.slf4j.LoggerFactory.bind(LoggerFactory.java:150)
     at org.slf4j.LoggerFactory.performInitialization(LoggerFactory.java:124)
     at org.slf4j.LoggerFactory.getILoggerFactory(LoggerFactory.java:412)
     at ch.qos.logback.classic.util.StatusViaSLF4JLoggerFactory.addStatus(StatusViaSLF4JLoggerFactory.java:32)
     at ch.qos.logback.classic.util.StatusViaSLF4JLoggerFactory.addInfo(StatusViaSLF4JLoggerFactory.java:20)
     at ch.qos.logback.classic.servlet.LogbackServletContainerInitializer.onStartup(LogbackServletContainerInitializer.java:32)