*/
private String projectSingleField(IndexReader reader, String fieldName, Term term) throws IOException {
String projection = null;
for ( AtomicReaderContext leaf : reader.leaves() ) {
final AtomicReader atomicReader = leaf.reader();
final DocsEnum termDocsEnum = atomicReader.termDocsEnum( term );
while ( termDocsEnum.nextDoc() != DocsEnum.NO_MORE_DOCS ) {
final int docID = termDocsEnum.docID();
org.apache.lucene.document.Document document = reader.document( docID );
String value = document.get( fieldName );
Assert.assertNull( "duplicate matches found! This method assumes a single document will match the Term.", projection );