NonApiType reported for overriden methods

[Marcono1234]

Version

Error Prone: 2.31.0
JDK: 17

Description

The pattern NonApiType is reported for overridden methods for some types (e.g. ArrayList). For overridden methods it might not be possible to change the types. Maybe it is possible if type variables are used but that might imply other changes, and might therefore be out of scope for NonApiType.

Example

import java.util.ArrayList;

public abstract class ObjectFactory<T> {
  public abstract T create();

  @SuppressWarnings("unchecked")
  public static <T> ObjectFactory<T> createFactory(Class<T> c) {
    if (c.isAssignableFrom(ArrayList.class)) {
      return (ObjectFactory<T>) new ObjectFactory<ArrayList<Object>>() {
        @Override
        // ERROR-PRONE: Reports NonApiType here
        public ArrayList<Object> create() {
          return new ArrayList<>();
        }
      };
    }
    throw new UnsupportedOperationException();
  }
}

Expected behavior

Either overridden methods should be completely ignored, or maybe more sophisticated detection is needed which only reports this pattern if a covariant return type (more specific return type than needed) is used. For example if a method List<String> getResult() is overridden as ArrayList<String> getResult().