Since the fix for JDK-8078093 there has been a regression in the behavior for stuck expressions. For example, this program fails to compile:

import java.util.function.Consumer;
import java.nio.ByteBuffer;

class Foo {
    Foo(Consumer<ByteBuffer> cb) {
    }

    public static void main(String[] args) {
        Foo foo = new Foo((b -> System.out.println(asString(b))));
    }

    static String asString(ByteBuffer buf) {
        return null;
    }
}

But compiles if the parenthesis are removed from around the lambda.

Also, this other program:

interface Foo1 {
   Object m(String s);
}

interface Foo2 {
   String m(String s);
}

class Test {
   void m(Foo1 f1) { }
   void m(Foo2 f2) { }

   void test() {
      m(x->"");
      m((x->""));
   }
}

Only reports one ambiguity error instead of two.