public static boolean matchingQualifier(final Cell left, final byte[] buf) {
    if (buf == null) {
      return left.getQualifierLength() == 0;
    }
    return PrivateCellUtil.matchingQualifier(left, buf, 0, buf.length);
  }
Finds if the qualifier part of the cell and the KV serialized byte[] are equal.
@return true if the qualifier matches, false otherwise
hbase-common/src/main/java/org/apache/hadoop/hbase/CellUtil.java