@Nullable
  public static PsiExpression getEffectiveQualifier(@NotNull PsiReferenceExpression ref) {
    PsiExpression qualifier = ref.getQualifierExpression();
    if (qualifier != null) return qualifier;
    PsiMember member = tryCast(ref.resolve(), PsiMember.class);
    if (member == null) {
      // Reference resolves to non-member: probably variable/parameter/etc.
      return null;
    }
    return getEffectiveQualifier(ref, member);
  }
@Nullable
  public static PsiExpression getEffectiveQualifier(@NotNull PsiReferenceExpression ref)