@Override
  public int hashCode() {
    int hashCode = 1;

    hashCode = hashCode * 8191 + ((isSetFamily()) ? 131071 : 524287);
    if (isSetFamily())
      hashCode = hashCode * 8191 + family.hashCode();

    hashCode = hashCode * 8191 + ((isSetQualifier()) ? 131071 : 524287);
    if (isSetQualifier())
      hashCode = hashCode * 8191 + qualifier.hashCode();

    hashCode = hashCode * 8191 + ((isSetTimestamp()) ? 131071 : 524287);
    if (isSetTimestamp())
      hashCode = hashCode * 8191 + org.apache.thrift.TBaseHelper.hashCode(timestamp);

    return hashCode;
  }
Returns true if field corresponding to fieldID is set (has been assigned a value) and false otherwise
hbase-thrift/src/main/java/org/apache/hadoop/hbase/thrift2/generated/TColumn.java