Upgrade to slf4j 1.7.23

February 15th, 2017 - Release of SLF4J 1.7.23

Update to SLF4J version 1.7.23 to enable slf4j-log4j12 to run under Java 9.

When running under Java 9, log4j version 1.2.x is unable to correctly parse the "java.version" system property. Assuming an inccorect Java version, it proceeded to disable its MDC functionality. The slf4j-log4j12 module shipping in this release fixes the issue by tweaking MDC internals by reflection, allowing log4j to run under Java 9. See also SLF4J-393.

Fixed issue EventRecodingLogger not saving marker data in the event. This issue was reported in SLF4J-379 by Manish Soni with Jonas Neukomm providing the relevant PR.

The slf4j-simple module now uses the latest reference to System.out or System.err. In previous releases the reference was set at the beginning and re-used. This change fixes SLF4J-389 reported by Igor Polevoy.