The fix for JDK-8171981 brought in JEP-286 code. A problem with the use of == was noted and traced to the use of .stream().map(...).collect(...) on a List. These lists are javac lists not java.util lists and == is a common usage but requires that .map be used instead. This was fixed in the commit for JDK-8171981.

However, there was a second use of .stream().map(...).collect(...) with == which was not corrected.

                Type outer = t.getEnclosingType();
                Type outer1 = visit(outer, upward);
                List<Type> typarams = t.getTypeArguments();
                List<Type> typarams1 = typarams.stream()
                        .map(ta -> mapTypeArgument(ta, upward))
                        .collect(List.collector());
                if (typarams1.stream().anyMatch(ta -> ta.hasTag(BOT))) {
                    //not defined
                    return syms.botType;
                }
                if (outer1 == outer && typarams1 == typarams) return t;

This bug is to fix that usage.