#vulnerable code 
                              @Test
  public void testDuplicateMapIds() throws Exception {
    MappingFileReader fileReader = new MappingFileReader("duplicateMapIdsMapping.xml");
    MappingFileData mappingFileData = fileReader.read();

    try {
      parser.processMappings(mappingFileData.getClassMaps(), new Configuration());
      fail("should have thrown exception");
    } catch (Exception e) {
      assertTrue("invalid exception thrown", e.getMessage().indexOf("Duplicate Map Id") != -1);
    }
  } 
                            #location 4 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                              @Test
  public void testDuplicateMapIds() throws Exception {
    MappingFileReader fileReader = new MappingFileReader(XMLParserFactory.getInstance());
    MappingFileData mappingFileData = fileReader.read("duplicateMapIdsMapping.xml");

    try {
      parser.processMappings(mappingFileData.getClassMaps(), new Configuration());
      fail("should have thrown exception");
    } catch (Exception e) {
      assertTrue("invalid exception thrown", e.getMessage().indexOf("Duplicate Map Id") != -1);
    }
  }