#vulnerable code 
                                @Test
    public void testXmlRecordReading() throws Exception {
        String expectedDataSourceName = dataSource.getAbsolutePath();

        XmlRecord xmlRecord = xmlFileRecordReader.readRecord();
        assertThat(xmlRecord.getHeader().getNumber()).isEqualTo(1L);
        assertThat(xmlRecord.getHeader().getSource()).isEqualTo(expectedDataSourceName);
        assertThat(xmlRecord.getPayload()).isEqualTo("<data>1</data>");

        xmlRecord = xmlFileRecordReader.readRecord();
        assertThat(xmlRecord.getHeader().getNumber()).isEqualTo(2L);
        assertThat(xmlRecord.getHeader().getSource()).isEqualTo(expectedDataSourceName);
        assertThat(xmlRecord.getPayload()).isEqualTo("<data>2</data>");

        xmlRecord = xmlFileRecordReader.readRecord();
        assertThat(xmlRecord.getHeader().getNumber()).isEqualTo(3L);
        assertThat(xmlRecord.getHeader().getSource()).isEqualTo(expectedDataSourceName);
        assertThat(xmlRecord.getPayload()).isEqualTo("<data>3</data>");

        xmlRecord = xmlFileRecordReader.readRecord();
        assertThat(xmlRecord.getHeader().getNumber()).isEqualTo(4L);
        assertThat(xmlRecord.getHeader().getSource()).isEqualTo(expectedDataSourceName);
        assertThat(xmlRecord.getPayload()).isEqualTo("<data>4</data>");

        xmlRecord = xmlFileRecordReader.readRecord();
        assertThat(xmlRecord.getHeader().getNumber()).isEqualTo(5L);
        assertThat(xmlRecord.getHeader().getSource()).isEqualTo(expectedDataSourceName);
        assertThat(xmlRecord.getPayload()).isEqualTo("<data>5</data>");

        xmlRecord = xmlFileRecordReader.readRecord();
        assertThat(xmlRecord).isNull();
    } 
                            #location 16 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                @Test
    public void testXmlRecordReading() throws Exception {
        // given
        dataSource = new File("src/test/resources/data.xml");
        xmlFileRecordReader = new XmlFileRecordReader(dataSource, "data");
        xmlFileRecordReader.open();
        String expectedDataSourceName = dataSource.getAbsolutePath();

        // when
        XmlRecord xmlRecord1 = xmlFileRecordReader.readRecord();
        XmlRecord xmlRecord2 = xmlFileRecordReader.readRecord();
        XmlRecord xmlRecord3 = xmlFileRecordReader.readRecord();
        XmlRecord xmlRecord4 = xmlFileRecordReader.readRecord();

        // then
        assertThat(xmlRecord1.getHeader().getNumber()).isEqualTo(1L);
        assertThat(xmlRecord1.getHeader().getSource()).isEqualTo(expectedDataSourceName);
        assertThat(xmlRecord1.getPayload()).isEqualTo("<data>1</data>");

        assertThat(xmlRecord2.getHeader().getNumber()).isEqualTo(2L);
        assertThat(xmlRecord2.getHeader().getSource()).isEqualTo(expectedDataSourceName);
        assertThat(xmlRecord2.getPayload()).isEqualTo("<data>2</data>");

        assertThat(xmlRecord3.getHeader().getNumber()).isEqualTo(3L);
        assertThat(xmlRecord3.getHeader().getSource()).isEqualTo(expectedDataSourceName);
        assertThat(xmlRecord3.getPayload()).isEqualTo("<data>3</data>");

        assertThat(xmlRecord4).isNull();
    }