enviroment:
lucene2.9.2 + bobo-browse2.5.0 + zoie2.0

create index:
Document doc=new Document();
doc.add(new NumericField("calling", Store.YES, true).setIntValue(20));
......

search index:
List<FacetHandler<?>> handlerList = new ArrayList<FacetHandler<?>>();
handlerList.add(new SimpleFacetHandler("calling", new PredefinedTermListFactory<Integer>(Integer.class)));
IndexReaderDecorator decorator = new BoboIndexReaderDecorator(handlerList);
ZoieSystem indexingSystem = new ZoieSystem(idxDir, myInterpreter, decorator, analyzer, similarity, 1000, 300000, true);

BrowseRequest br = new BrowseRequest();
br.setCount(count);
br.setOffset(offset);
br.setQuery(query);
br.setFetchStoredFields(true);
br.setSort(sort);

br.setFacetSpec("calling", new FacetSpec());
           
List<ZoieIndexReader<BoboIndexReader>> readerList = indexingSystem.getIndexReaders();
MultiBoboBrowser browser = new MultiBoboBrowser(BoboBrowser.createBrowsables(ZoieIndexReader.extractDecoratedReaders(readerList)));
BrowseResult result = browser.browse(br);

[com.browseengine.bobo.api.BoboIndexReader]-[ERROR] facet load failed: reqdegreeid: For input string: "`
at java.lang.NumberFormatException.forInputString(NumberFormatException.java:48)
at java.lang.Integer.parseInt(Integer.java:449)
at java.lang.Integer.parseInt(Integer.java:499)
at com.browseengine.bobo.facets.data.TermIntList.parse(TermIntList.java:23)
at com.browseengine.bobo.facets.data.TermIntList.add(TermIntList.java:45)
at com.browseengine.bobo.facets.data.FacetDataCache.load(FacetDataCache.java:122)
at com.browseengine.bobo.facets.impl.SimpleFacetHandler.load(SimpleFacetHandler.java:174)
at com.browseengine.bobo.facets.impl.SimpleFacetHandler.load(SimpleFacetHandler.java:31)
at com.browseengine.bobo.facets.FacetHandler.load(FacetHandler.java:143)
at com.browseengine.bobo.facets.FacetHandler.loadFacetData(FacetHandler.java:148)
at com.browseengine.bobo.api.BoboIndexReader.loadFacetHandler(BoboIndexReader.java:380)
at com.browseengine.bobo.api.BoboIndexReader.loadFacetHandlers(BoboIndexReader.java:400)
at com.browseengine.bobo.api.BoboIndexReader.facetInit(BoboIndexReader.java:589)
at com.browseengine.bobo.api.BoboIndexReader.facetInit(BoboIndexReader.java:581)
at com.browseengine.bobo.api.BoboIndexReader.getInstanceAsSubReader(BoboIndexReader.java:163)
at com.browseengine.bobo.api.BoboIndexReader.getInstanceAsSubReader(BoboIndexReader.java:154)
at com.browseengine.bobo.service.impl.BoboIndexReaderDecorator.decorate(BoboIndexReaderDecorator.java:49)
at com.browseengine.bobo.service.impl.BoboIndexReaderDecorator.decorate(BoboIndexReaderDecorator.java:17)
at proj.zoie.api.ZoieSegmentReader.<init>(ZoieSegmentReader.java:99)
at proj.zoie.api.ZoieMultiReader.init(ZoieMultiReader.java:76)
at proj.zoie.api.ZoieMultiReader.<init>(ZoieMultiReader.java:50)
at proj.zoie.impl.indexing.internal.IndexReaderDispenser$InternalIndexReader.<init>(IndexReaderDispenser.java:46)
at proj.zoie.impl.indexing.internal.IndexReaderDispenser.newReader(IndexReaderDispenser.java:137)
at proj.zoie.impl.indexing.internal.IndexReaderDispenser.getNewReader(IndexReaderDispenser.java:197)
at proj.zoie.impl.indexing.internal.IndexReaderDispenser.<init>(IndexReaderDispenser.java:80)
at proj.zoie.impl.indexing.internal.DiskSearchIndex.<init>(DiskSearchIndex.java:54)
at proj.zoie.impl.indexing.internal.SearchIndexManager.<init>(SearchIndexManager.java:73)
at proj.zoie.impl.indexing.ZoieSystem.<init>(ZoieSystem.java:182)
at proj.zoie.impl.indexing.ZoieSystem.<init>(ZoieSystem.java:158)
at proj.zoie.impl.indexing.ZoieSystem.<init>(ZoieSystem.java:117)
at proj.zoie.impl.indexing.ZoieSystem.<init>(ZoieSystem.java:101)