public InternalDistributedSystem build() {
      ConnectionConfigImpl connectionConfig = new ConnectionConfigImpl(configProperties);

      InternalDistributedSystem internalDistributedSystem =
          new InternalDistributedSystem(connectionConfig, statisticsManagerFactory,
              FunctionStatsManager::new);

      internalDistributedSystem.config =
          new RuntimeDistributionConfigImpl(internalDistributedSystem);
      internalDistributedSystem.dm = distributionManager;
      internalDistributedSystem.isConnected = true;

      return internalDistributedSystem;
    }
Builds instance without initializing it for testing.
geode-core/src/main/java/org/apache/geode/distributed/internal/InternalDistributedSystem.java