Noted by @methompson in #4121 (comment)

class MyClass {
  //
  method1(String a) {
    //
  }
  //
}

{
	"id": 202,
	"jsonrpc": "2.0",
	"result": [
		{
			"endLine": 1,
			"startLine": 0
		},
		{
			"endLine": 4,
			"startLine": 2
		}
	]
}

Here, the folding for the class goes from line 0-1 and doesn't actually cover the class at all. If you remove the first comment, it results in the folding for class not appearing at all.