#vulnerable code 
                                public BytePointer putString(String s) {
        byte[] bytes = s.getBytes();
        //capacity(bytes.length+1);
        asBuffer().put(bytes).put((byte)0);
        return this;
    } 
                            #location 4 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                public BytePointer putString(String s) {
        byte[] bytes = s.getBytes();
        return put(bytes).put(bytes.length, (byte)0);
    }