private FileResourceCrawler buildCrawler(ArrayBlockingQueue<FileResource> queue, Node node, Map<String, String> runtimeAttributes) {
        Map<String, String> attrs = XMLDOMUtil.mapifyAttrs(node, runtimeAttributes);
        String className = attrs.get("builderClass");
        if (className == null) {
            throw new RuntimeException("Need to specify class name in crawler element");
        }

        ICrawlerBuilder builder = ClassLoaderUtil.buildClass(ICrawlerBuilder.class, className);
        return builder.build(node, runtimeAttributes, queue);
    }
Builds a FileResourceBatchProcessor from runtime arguments and a
document node of a configuration file.  With the exception of the QueueBuilder,
the builders choose how to adjudicate between
runtime arguments and the elements in the configuration file.

@param docElement                document element of the xml config file
@param incomingRuntimeAttributes runtime arguments
@return FileResourceBatchProcessor
tika-batch/src/main/java/org/apache/tika/batch/builders/BatchProcessBuilder.java