Empty formatter settings disable rules

I have the google style eclipse settings activated in my user settings.
By accident, I've saved an empty string in my formatter settings of my workspace which lead to

"java.format.settings.url": ""

in my workspace settings.json. I did this in the UI so I didn't notice at first.
Apparently this overwrites the user settings.json file, formatting was done by the default formatting rules and not the ones specified in my user settings.json.

I'm not sure if this is intended or if it's actually related to how vscode (and not this plugin) handle settings values.

Environment

• Operating System: macOS Catalina 10.15.1
• JDK version: 1.8.0_202
• Visual Studio Code version: 1.41.1
• Java extension version: 0.55.1

Steps To Reproduce

1. Set custom formatting rules in your user settings.json

"java.format.settings.url": "/PATH/TO/CUSTOM/RULES"

2. Set custom formatting rules in a project's settings.json to empty string:

"java.format.settings.url": ""

Current Result

Empty-string 'java.format.settings.url' in workspace lead to usage of default rules of the plugin and not the settings url set in the user settings.json.

Expected Result

Empty-string should be a value that is ignored and therefore use the url defined in the user settings.json

Additional Informations

The only way to notice that there is an empty string in the workspace settings.json in the UI is the message that it is 'Modified in: Workspace' but the UI itself shows the same value as it would when it wasn't defined in the first place (empty string).

首先跟踪扩展在工作区值为空字符串时如何读取和应用 java.format.settings.url 配置。确认空的工作区值是否可以回退到用户值，并根据复现步骤验证其行为；issue 中未指定源文件或测试。