code: public AutoComplete autoCompleteEntry(String prefix) {
          final AutoComplete directoryAutoComplete = autoCompleteDirectory(prefix);
          final AutoComplete commandAutoComplete = autoCompleteCommand(prefix);
          return directoryAutoComplete.union(commandAutoComplete);
      }
docs: Auto complete the given prefix with child directory or command possibilities.
  
  @param prefix Prefix to offer auto complete for.
  @return Auto complete for child entries (either {@link CliDirectory} or {@link CliCommand})
  that start with the given prefix. Case insensitive.