// Find the ValueParser for the current key.
        String key = keyAndValue.get(0);
        ValueParser valueParser = VALUE_PARSERS.get(key);
        checkArgument(valueParser != null, "unknown key %s", key);

        String value = keyAndValue.size() == 1 ? null : keyAndValue.get(1);
        valueParser.parse(spec, key, value);
      }
    }

    return spec;
  }

        // Find the ValueParser for the current key.
        String key = keyAndValue.get(0);
        ValueParser valueParser = VALUE_PARSERS.get(key);
        checkArgument(valueParser != null, "unknown key %s", key);

        String value = keyAndValue.size() == 1 ? null : keyAndValue.get(1);
        valueParser.parse(spec, key, value);
      }
    }

    return spec;
  }