code: @javax.annotation.Nullable
    public String get(String key) {
      for (Entry entry : getEntries()) {
        if (entry.getKey().equals(key)) {
          return entry.getValue();
        }
      }
      return null;
    }
docs: Returns the value to which the specified key is mapped, or null if this map contains no mapping
  for the key.
  
  @param key with which the specified value is to be associated
  @return the value to which the specified key is mapped, or null if this map contains no mapping
  for the key.
  @since 0.16