After switching to standard mode, language server exits

[provide a description of the issue]
Starting the server in lightweight mode, then switching to standard mode causes the server to exit after a few minutes.

Environment

• Operating System:
  Linux Mint
  4.15.0-112-generic GNU/Linux

• JDK version:
  java --version
  openjdk 11.0.8 2020-07-14
  OpenJDK Runtime Environment (build 11.0.8+10-post-Ubuntu-0ubuntu118.04.1)
  OpenJDK 64-Bit Server VM (build 11.0.8+10-post-Ubuntu-0ubuntu118.04.1, mixed mode, sharing)

• Visual Studio Code version:
  Version: 1.47.3
  Commit: 91899dcef7b8110878ea59626991a18c8a6a1b3e
  Date: 2020-07-23T15:51:39.791Z
  Electron: 7.3.2
  Chrome: 78.0.3904.130
  Node.js: 12.8.1
  V8: 7.8.279.23-electron.0
  OS: Linux x64 4.15.0-112-generic

• Java extension version:
  0.65.0

Steps To Reproduce

1. Project is opened with language server in lightweight mode.
   Server seems to be working fine, messages are being sent and responses are being received OK.

2. Switch language server to standard mode
   Server seems to start, only to exit after a few minutes.
   [Trace - 5:08:38 AM] Sending request 'shutdown - (4)'.
   [Trace - 5:08:38 AM] Received response 'shutdown - (4)' in 50ms.
   Result: {}

[Trace - 5:08:38 AM] Sending notification 'exit'.
No parameters provided.

[Please attach a sample project reproducing the error]
Sorry, unable to do so due to company restrictions.

[Please attach [logs]]
-1596705089486.log

Additional Informations

从附带的 language-server 日志开始，复现所报告的序列：以轻量模式启动，切换到标准模式，并观察之后的 shutdown 和 exit 通知。完成的标准是服务器在模式切换后仍保持运行；未提供示例项目或特定源文件。