#vulnerable code 
                                @Test
    public void stemEndingTest1() throws IOException {
        TurkishMorphology morphology = TurkishMorphology.builder().addDictionaryLines("bakmak", "gelmek").build();
        List<String> endings = Lists.newArrayList("acak", "ecek");
        StemEndingGraph graph = new StemEndingGraph(morphology, endings);
        CharacterGraphDecoder spellChecker = new CharacterGraphDecoder(graph.stemGraph);
        List<ScoredItem<String>> res = spellChecker.getSuggestionsWithScores("bakcaak");
        for (ScoredItem<String> re : res) {
            System.out.println(re.item);
        }
    } 
                            #location 7 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                @Test
    public void stemEndingTest1() throws IOException {
        TurkishMorphology morphology = TurkishMorphology.builder().addDictionaryLines("bakmak", "gelmek").build();
        List<String> endings = Lists.newArrayList("acak", "ecek");
        StemEndingGraph graph = new StemEndingGraph(morphology, endings);
        CharacterGraphDecoder spellChecker = new CharacterGraphDecoder(graph.stemGraph);
        List<String> res = spellChecker.getSuggestions("bakcaak");
        Assert.assertEquals(1, res.size());
        Assert.assertEquals("bakacak", res.get(0));
    }