@PluginBuilderFactory
  public static <B extends LogWriterAppender.Builder<B>> B newBuilder() {
    return new LogWriterAppender.Builder<B>().asBuilder();
  }
appendLog used to be controlled by undocumented system property gemfire.append-log
geode-log4j/src/main/java/org/apache/geode/logging/log4j/internal/impl/LogWriterAppender.java