@Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;

        SparseSketch sketch = (SparseSketch) o;

        if (!values.equals(sketch.values)) return false;

        return true;
    }
Serializes the Sketch.

Serialization format
==================
Number of elements:      4 bytes
Elements:            N * 4 bytes
@param buf Serializer
searchlib/src/main/java/com/yahoo/searchlib/aggregation/hll/SparseSketch.java