#vulnerable code 
                                @Test
    public void testObjectEncode() throws Exception {
        Base64 b64 = new Base64();
        assertEquals("SGVsbG8gV29ybGQ=", new String(b64.encode("Hello World".getBytes("UTF-8"))));
    } 
                            #location 4 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                @Test
    public void testObjectEncode() throws Exception {
        Base64 b64 = new Base64();
        assertEquals("SGVsbG8gV29ybGQ=", new String(b64.encode("Hello World".getBytes(Charsets.UTF_8))));
    }