src/main/java/org/jcodec/containers/mkv/MKVType.java
public static MKVType getParent(MKVType t){
          for(Entry<MKVType, Set<MKVType>> ent : children.entrySet()){
              if (ent.getValue().contains(t))
                  return ent.getKey();
          }
          return null;
      }
public static MKVType getParent(MKVType t){
          for(Entry<MKVType, Set<MKVType>> ent : children.entrySet()){
              if (ent.getValue().contains(t))
                  return ent.getKey();
          }
          return null;
      }
TODO: this may be optimized of-course if it turns out to be a frequently called method