@Override
      public int size() {
        return m.size();
      }
Add Bytes map to config list. This map is generally created by HTableDescriptor or
HColumnDescriptor, but can be abstractly used. The added configuration overrides the previous
ones if there are name collisions. Bytes map
@return this, for builder pattern
hbase-common/src/main/java/org/apache/hadoop/hbase/CompoundConfiguration.java