public DocumentProcessing documentProcessing() {
        DocumentProcessingHandler docprocHandler = (DocumentProcessingHandler) container
                .getRequestHandlerRegistry()
                .getComponent(DocumentProcessingHandler.class.getName());

        if (docprocHandler == null) {
            throw new UnsupportedOperationException("This JDisc does not have 'document-processing' configured.");
        }
        return new DocumentProcessing(docprocHandler);
    }
Returns a {@link DocumentProcessing}, used to process objects of type {@link com.yahoo.document.Document},
{@link com.yahoo.document.DocumentRemove} and {@link com.yahoo.document.DocumentUpdate}.

@return a DocumentProcessing instance
@throws UnsupportedOperationException if this JDisc does not have document processing configured
application/src/main/java/com/yahoo/application/container/JDisc.java