public boolean has(byte[] family, byte[] qualifier) {
    return has(family, qualifier, this.ts, HConstants.EMPTY_BYTE_ARRAY, true, true);
  }
A convenience method to determine if this object's familyMap contains a value assigned to the
given family &amp; qualifier. Both given arguments must match the KeyValue object to return
true.
@param family    column family
@param qualifier column qualifier
@return returns true if the given family and qualifier already has an existing KeyValue object
        in the family map.
hbase-client/src/main/java/org/apache/hadoop/hbase/client/Mutation.java