March 29th, 2016 - Release of SLF4J 1.7.20
Fixed initialization problem encountered on the Google App Engine platform with SLF4J version 1.7.19 but not other versions. The problem was reported in SLF4J-363 by Osvaldo Pinali Doederlein.
March 14th, 2016 - Release of SLF4J 1.7.19
Fixed NullPointerException thrown by org.slf4j.helpers.SubstituteLogger.isDelegateEventAware(SubstituteLogger.java:353). This issue was reported by Jeffrey Zhao in SLF4J-361.
Initialization of the slf4j-log4j12 module is now thread safe fixing SLF4J-358.
Initialization of the slf4j-jdk14 module is now thread safe fixing SLF4J-359.