code: public synchronized boolean add(String key, T value) {
          if (key.length() > 3 && key.endsWith(WILDCARD) && key.charAt(key.length() - 2) != '.') {
              throw new IllegalArgumentException("Unsupported use of wildcard in key " + key);
          }
  
          // Find the key in the structure (build out to it)
          Node<T> current = internalFind(key, false);
  
          // Return false if the key already exists
          if (current.getValue() != null)
              return false;
  
          // Set the value and return true
          current.setValue(value);
          return true;
      }
docs: Add a new value using the given key.
  
  @param key Key, this is string
  @param value Value to associate with the key
  @return true if key successfully added, false if there was a collision.