Our own api to highlight a single document field, passing in the query terms, and get back our own Snippet object
*/
public Snippet[] highlightDoc(String field, BytesRef[] terms, IndexSearcher searcher, int docId, int maxPassages) throws IOException {
IndexReader reader = searcher.getIndexReader();
IndexReaderContext readerContext = reader.getContext();
List<LeafReaderContext> leaves = readerContext.leaves();
String[] contents = new String[]{loadCurrentFieldValue()};
Map<Integer, Object> snippetsMap = highlightField(field, contents, getBreakIterator(field), terms, new int[]{docId}, leaves, maxPassages);
//increment the current value index so that next time we'll highlight the next value if available