Optional input in a Java custom processor

>  Hi
>
>  I have a custom processor that has an optional input.  I
> mean one can write either of the following:
>
>    <p:processor name="my:custom-processor">
>       <p:input name="in">
>          ...
>       </p:input>
>       <p:output name="data" ref="..."/>
>    </p:processor>
>
>    <p:processor name="my:custom-processor">
>       <p:output name="data" ref="..."/>
>    </p:processor>
>
>
>  The relevant parts look like this:
>
>    public class CustomProcessor
>            extends SimpleProcessor
>    {
>        public CustomProcessor()
>        {
>            addInputInfo(new ProcessorInputOutputInfo("in"));
>            addOutputInfo(new ProcessorInputOutputInfo("data"));
>        }
>
>        public void generateData(PipelineContext ctxt,
>                                 ContentHandler out)
>                throws SAXException
>        {
>            ContentHandler handler = ...;
>            readInputAsSAX(context, "in", handler);
>        }
>    }
>
>  But in the case the XPL doesn't pass the optional input
> "in", the methods readInput*() throw an exception: «Cannot
> find input "in".»
>
>  Is there any way to tag the input as optional in a custom
> processor?
>
>  Regards,
>
> --drkm
>
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