code: @Override
  	public void write(final DataOutput out) throws IOException {
  		out.writeInt(this.map.size());
  		for (final Entry<K, V> entry : this.map.entrySet()) {
  			entry.getKey().write(out);
  			entry.getValue().write(out);
  		}
  	}
docs: /*
  (non-Javadoc)
  @see eu.stratosphere.nephele.io.IOReadableWritable#write(java.io.DataOutput)