logback-android/src/main/java/ch/qos/logback/classic/util/LogbackMDCAdapter.java
public Map<String, String> getCopyOfContextMap() {
    Map<String, String> hashMap = copyOnThreadLocal.get();
    if (hashMap == null) {
      return null;
    } else {
      return new HashMap<String, String>(hashMap);
    }
  }
public Map<String, String> getCopyOfContextMap() {
    Map<String, String> hashMap = copyOnThreadLocal.get();
    if (hashMap == null) {
      return null;
    } else {
      return new HashMap<String, String>(hashMap);
    }
  }
Return a copy of the current thread's context map. Returned value may be
null.