public ModifyableColumnFamilyDescriptor setConfiguration(String key, String value) {
      if (value == null || value.length() == 0) {
        configuration.remove(key);
      } else {
        configuration.put(key, value);
      }
      return this;
    }
Setter for storing a configuration setting in {@link #configuration} map.
@param key   Config key. Same as XML config key e.g. hbase.something.or.other.
@param value String value. If null, removes the configuration.
@return this (for chained invocation)
hbase-client/src/main/java/org/apache/hadoop/hbase/client/ColumnFamilyDescriptorBuilder.java