Where can I find test case automation using "Appium Flutter plugin" using Java

I am using Java 15, Appium 2.0.0.beta57, TestNG, with CucumberBDD feature files to test a flutter application. The version of Flutter installed on my system is 3.7.12.
I came to know about “Appium Flutter plugin”, and it’s element locator method ByValueKey(key) interested me very much, because that is the only way our DEV team is going to provide us, the QA team.

Will any one help me, with the location of the documentation, tutorials and API of that plugin.

Appreciate your help.

Have you looked at the github repo? They have examples: