Consider
/// This is a comment for the library.
library hello;

class T1 {
  bool foo = true;
  bool bar() => true;
}

class T2 extends T1 {
}

main() {
  print(new T2.blah(true));
}

which produces JSON with the qualified name set on foo but not the inheritedFrom. For the bar method it does set the inheritedFrom field.

  "inheritedVariables": {
    "foo": {
      "name": "foo",
      "qualifiedName": "hello.T1.foo",
      "comment": "",
      "final": "false",
      "static": "false",
      "constant": "false",
      "type": [
        {
          "outer": "dart-core.bool",
          "inner": [
            
          ]
        }
      ],
      "annotations": [
        
      ]
    }
  },