#vulnerable code 
                                public void testDecodePadOnlyChunked() {
        assertTrue(Base64.decodeBase64("====\n".getBytes()).length == 0);
        assertEquals("", new String(Base64.decodeBase64("====\n".getBytes())));
        // Test truncated padding
        assertTrue(Base64.decodeBase64("===\n".getBytes()).length == 0);
        assertTrue(Base64.decodeBase64("==\n".getBytes()).length == 0);
        assertTrue(Base64.decodeBase64("=\n".getBytes()).length == 0);
        assertTrue(Base64.decodeBase64("\n".getBytes()).length == 0);
    } 
                            #location 2 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                public void testDecodePadOnlyChunked() throws UnsupportedEncodingException {
        assertTrue(Base64.decodeBase64("====\n".getBytes("UTF-8")).length == 0);
        assertEquals("", new String(Base64.decodeBase64("====\n".getBytes("UTF-8"))));
        // Test truncated padding
        assertTrue(Base64.decodeBase64("===\n".getBytes("UTF-8")).length == 0);
        assertTrue(Base64.decodeBase64("==\n".getBytes("UTF-8")).length == 0);
        assertTrue(Base64.decodeBase64("=\n".getBytes("UTF-8")).length == 0);
        assertTrue(Base64.decodeBase64("\n".getBytes("UTF-8")).length == 0);
    }