private static Connection createConnection(Configuration cfg) {
    try {
      return ConnectionFactory.createConnection(cfg);
    } catch (IOException e) {
      throw new RuntimeException(e);
    }
  }
Creates AggregationClient with internally managed Connection, which will be used by methods
taking a {@link TableName} to create the necessary {@link Table} for the call. The Connection
will immediately be created will be closed when {@link #close()} is called. It's important to
call {@link #close()} when done with this AggregationClient and to otherwise treat it as a
shared Singleton.
@param cfg Configuration to use to create connection
hbase-endpoint/src/main/java/org/apache/hadoop/hbase/client/coprocessor/AggregationClient.java