title: Pass configuration parameter to custom Flink ProcessFunction
body: <p>I need to be able to pass in a configuration parameter to <code>MyFunction</code> which extends <code>ProcessFunction</code>. Is the only way for me to do that in my  parameter? I don't need it to be passed in with each element. Can I make use of the <code>open</code> method somehow?</p>
  <pre><code>public class MyProcessFunction extends ProcessFunction&lt;AbstractMap.SimpleEntry&lt;Row, RowTypeInfo&gt;, MyOutput&gt; {
  
      public void open(Configuration parameters) {
      }
  
      @Override
      public void processElement(AbstractMap.SimpleEntry&lt;Row, RowTypeInfo&gt; value, Context ctx, Collector&lt;MyOutput&gt; out) throws Exception {
  
  </code></pre>