App Inventor Extension

Hello All,
I hope you all are safe at home.
i am making firebase analytics extension. so can anyone help me how solve this problem i am using offline mit sources.
[javac] C:\appinventor-sources-master\appinventor\components\src\com\preet\FirebaseAnalytics\ error: package does not exist
[javac] import;
[javac] ^
[javac] Note: Some input files use or override a deprecated API.
[javac] Note: Recompile with -Xlint:deprecation for details.
[javac] 1 error
please help me to solve

This question has been asked before by several people. See if the following topic answers your question. If not, feel free to ask any additional questions.