#vulnerable code 
                                @Test
    public void testDecodePadOnly() {
        assertEquals(0, Base64.decodeBase64("====".getBytes(Charsets.UTF_8)).length);
        assertEquals("", new String(Base64.decodeBase64("====".getBytes(Charsets.UTF_8))));
        // Test truncated padding
        assertEquals(0, Base64.decodeBase64("===".getBytes(Charsets.UTF_8)).length);
        assertEquals(0, Base64.decodeBase64("==".getBytes(Charsets.UTF_8)).length);
        assertEquals(0, Base64.decodeBase64("=".getBytes(Charsets.UTF_8)).length);
        assertEquals(0, Base64.decodeBase64("".getBytes(Charsets.UTF_8)).length);
    } 
                            #location 3 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                @Test
    public void testDecodePadOnly() {
        assertEquals(0, Base64.decodeBase64("====".getBytes(CHARSET_UTF8)).length);
        assertEquals("", new String(Base64.decodeBase64("====".getBytes(CHARSET_UTF8))));
        // Test truncated padding
        assertEquals(0, Base64.decodeBase64("===".getBytes(CHARSET_UTF8)).length);
        assertEquals(0, Base64.decodeBase64("==".getBytes(CHARSET_UTF8)).length);
        assertEquals(0, Base64.decodeBase64("=".getBytes(CHARSET_UTF8)).length);
        assertEquals(0, Base64.decodeBase64("".getBytes(CHARSET_UTF8)).length);
    }