private Set<EnodeURL> loadStaticNodes() throws IOException {
    final Path staticNodesPath;
    if (staticNodesFile != null) {
      staticNodesPath = staticNodesFile.toAbsolutePath();
      if (!staticNodesPath.toFile().exists()) {
        throw new ParameterException(
            commandLine, String.format("Static nodes file %s does not exist", staticNodesPath));
      }
    } else {
      final String staticNodesFilename = "static-nodes.json";
      staticNodesPath = dataDir().resolve(staticNodesFilename);
    }
    logger.debug("Static Nodes file: {}", staticNodesPath);
    final Set<EnodeURL> staticNodes =
        StaticNodesParser.fromPath(staticNodesPath, getEnodeDnsConfiguration());
    logger.info("Connecting to {} static nodes.", staticNodes.size());
    logger.debug("Static Nodes = {}", staticNodes);
    return staticNodes;
  }
Metrics System used by Besu

@return Instance of MetricsSystem
app/src/main/java/org/hyperledger/besu/cli/BesuCommand.java