#fixed code
                                public VanillaMappedBytes put(T key, File path, long size, long index) {
        DataHolder data = this.cache.get(key);
        if(data != null) {
            data.close();
        } else {
            data = new DataHolder();
        }

        try {
            cleanup();

            data.recycle(
                VanillaMappedFile.readWrite(path, size),
                0,
                size,
                index);

            this.cache.put(key,data);
        } catch(IOException e) {
            LOGGER.warn("",e);
        }

        return data.bytes();
    }
#vulnerable code 
                                public VanillaMappedBytes put(T key, File path, long size, long index) {
        DataHolder data = this.cache.get(key);
        if(data != null) {
            data.close();
        } else {
            data = new DataHolder();
        }

        try {
            final Iterator<Map.Entry<T,DataHolder>> it = this.cache.entrySet().iterator();
            while(it.hasNext()) {
                Map.Entry<T,DataHolder> entry = it.next();
                if(entry.getValue().bytes().unmapped()) {
                    entry.getValue().close();
                    it.remove();
                }
            }

            data.recycle(
                VanillaMappedFile.readWrite(path, size),
                0,
                size,
                index);

            this.cache.put(key,data);
        } catch(IOException e) {
            LOGGER.warn("",e);
        }

        return data.bytes();
    } 
                            #location 13 
                            #vulnerability type NULL_DEREFERENCE