public String get(String key) {
        Map<String, String> map = inheritableThreadLocalMap.get();
        if ((map != null) && (key != null)) {
            return map.get(key);
        } else {
            return null;
        }
    }
Get the context identified by the <code>key</code> parameter.
slf4j-api/src/main/java/org/slf4j/helpers/BasicMDCAdapter.java