void writeIsSharedConfigurationEnabled(boolean isSharedConfigurationEnabled) {
    if (optionalFields == null) {
      return;
    }
    optionalFields.setProperty(IS_SHARED_CONFIG_ENABLED,
        Boolean.toString(isSharedConfigurationEnabled));
  }
Write the value for the optional field {@link #HOSTED_LOCATORS}.
geode-core/src/main/java/org/apache/geode/distributed/internal/StartupMessageData.java