private static void serializeDataArray(byte[] source, int length, Serializer buf) {
        buf.putInt(null, length);
        for (int i = 0; i < length; i++) {
            buf.putByte(null, source[i]);
        }
    }
Serializes the Sketch.

Serialization format
==================
Original size:     4 bytes
Compressed size:   4 bytes
Compressed data:   N * 1 bytes

Invariant:
     compressed size &lt;= original size

Special case:
     compressed size == original size =&gt; data is uncompressed

@param buf Serializer
searchlib/src/main/java/com/yahoo/searchlib/aggregation/hll/NormalSketch.java