@PluginFactory
  public static StreamAppender createAppender(
      @PluginAttribute("name") final String name,
      @PluginElement("Filter") final Filter filter,
      @PluginElement("Layout") Layout layout,
      @PluginAttribute(value = "ignoreExceptions", defaultBoolean = true) final boolean ignoreExceptions,
      @PluginAttribute(value = "usingAsyncLogger", defaultBoolean = false) final boolean usingAsyncLogger,
      @PluginAttribute("streamName") String streamName) {
    return new StreamAppender(name, filter, layout, ignoreExceptions, usingAsyncLogger, streamName);
  }
Setter for the number of partitions to create on a new StreamAppender stream. See also {@link #createAppender(String, Filter, Layout, boolean, boolean, String)} for when this is called.
Example: {@literal <param name="PartitionCount" value="4"/>}
@param partitionCount Configurable partition count.
samza-log4j2/src/main/java/org/apache/samza/logging/log4j2/StreamAppender.java