http://www.slf4j.org/manual.html#mdc
"If the undelying system does not offer MDC, then SLF4J will silently drop MDC information."

public final class Main {

public static void main(String[] args)

{ org.slf4j.MDC.put("test", "test"); System.out.println("not reached"); }

}

SLF4J: Failed to load class "org.slf4j.impl.StaticMDCBinder".
SLF4J: See http://www.slf4j.org/codes.html#no_static_mdc_binder for further details.
Exception in thread "main" java.lang.NoClassDefFoundError: org/slf4j/impl/StaticMDCBinder
at org.slf4j.MDC.<clinit>(MDC.java:70)
at Main.main(Main.java:4)