code: @Override
      public String getServerName() {
          String name = this.request.getVirtualHost();
          if (null == name) {
              name = "localhost";
          }
          if (TraceComponent.isAnyTracingEnabled() && tc.isDebugEnabled()) {
              Tr.debug(tc, "getServerName: " + name);
          }
          return name;
      }
docs: /*
  @see javax.servlet.ServletRequest#getServerName()