Is state:
Using the JUL-to-SLF4J-Bridge, only messages with a Level of INFO or higher are logged. All other messages are discarded.

Should be state:
Using the JUL-to-SLF4J-Bridge, all messages according to the logback-configuration should be logged.

Cause:
During initalization of the JUL-to-SLF4J-Bridge, the JUL-Logging configuration is resetted. During this operation the level of the root-Logger of JUL is set to the default-level of INFO (see Javadoc for reference).

Solution:
After resetting, the loglevel of the root-logger must be set to Level.ALL, so that JUL logs all messages and the SLF4J-Framework can decide what to log.

Code:
change the install()-method of the SLF4JBridgeHandler from
##############
public static void install()
{
LogManager.getLogManager().reset();
LogManager.getLogManager().getLogger("").addHandler(new SLF4JBridgeHandler());
}
##############
--> to
##############
public static void install()
{
LogManager.getLogManager().reset();

java.util.logging.Logger logger = java.util.logging.Logger.getLogger("");
logger.setLevel(Level.ALL);

LogManager.getLogManager().getLogger("").addHandler(new SLF4JBridgeHandler());
}