protected static BlockingService getService(final List<BlockingServiceAndInterface> services,
    final String serviceName) {
    BlockingServiceAndInterface bsasi = getServiceAndInterface(services, serviceName);
    return bsasi == null ? null : bsasi.getBlockingService();
  }
@param serviceName Some arbitrary string that represents a 'service'.
@param services    Available services and their service interfaces.
@return BlockingService that goes with the passed <code>serviceName</code>
hbase-server/src/main/java/org/apache/hadoop/hbase/ipc/RpcServer.java