What what is "project " referring to? (Intellij Plugin)

It says cannot resolve symbol.

Document currentDoc = FileEditorManager.getInstance(project).getSelectedTextEditor().getDocument();

Example 2:

StatusBar statusBar = WindowManager.getInstance().getStatusBar(project);
if (statusBar != null) statusBar.addWidget(widget, [Anchor], [disposable]);

Solution

This is the method i use and recommend:

AnActionEvent.getData(LangDataKeys.PROJECT);

You can include it like that:

AnActionEvent.getProject()

The answer is in the comments:

Refer to these: