public Repository(TenantInfo tenantInfo, IConnectionStringBuilder connStringBuilder)
{
  tenantAwareConnString = connStringBuilder.GetConnectionStringForTenant(tenantInfo.TenantName);
}

public class ConnectionStringBuilder
{
  public ConnectionStringBuilder(ITenantAwareConnStringBuilder tenantAwareConnStringBuilder,
    IDbConfigProvider dbConfigProvider)
  {
  }
  
  public string GetConnectionStringForTenant(string tenantName)
  {
    return tenantAwareConnStringBuilder.
      .UseServer(dbConfigProvider.Server)
      .UseCredentials(dbConfigProvider.Username, dbConfigProvider.Password)
      .ForTenant(tenantName)
      .Build();
  }
}