Given the following Testcase:

import java.util.Collection;
import java.util.stream.Collectors;

public class TestClass<E>
{
    private Collection<E> coll;

    public void addAll(final Collection<? extends E> c) {
        coll.addAll(c.stream().collect(Collectors.toList()));
    }
}

My expected behaviour is for this to compile correctly, which it does in Java 8 u5 and u11. If you try and compile this class with javac from u20 then it is unable to find the collect() override correctly. Failing with the following error message.

TestClass.java:9: error: no suitable method found for collect(Collector<Object,CAP#1,List<Object>>)
        coll.addAll(c.stream().collect(Collectors.toList()));
                              ^
    method Stream.<R#1>collect(Supplier<R#1>,BiConsumer<R#1,? super CAP#2>,BiConsumer<R#1,R#1>) is not applicable
      (cannot infer type-variable(s) R#1
        (actual and formal argument lists differ in length))
    method Stream.<R#2,A>collect(Collector<? super CAP#2,A,R#2>) is not applicable
      (cannot infer type-variable(s) R#2,A,CAP#3,T#2
        (argument mismatch; Collector<CAP#2,CAP#4,List<CAP#2>> cannot be converted to Collector<? super CAP#2,CAP#4,List<CAP#2>>))
  where R#1,T#1,E,R#2,A,T#2 are type-variables:
    R#1 extends Object declared in method <R#1>collect(Supplier<R#1>,BiConsumer<R#1,? super T#1>,BiConsumer<R#1,R#1>)
    T#1 extends Object declared in interface Stream
    E extends Object declared in class TestClass
    R#2 extends Object declared in method <R#2,A>collect(Collector<? super T#1,A,R#2>)
    A extends Object declared in method <R#2,A>collect(Collector<? super T#1,A,R#2>)
    T#2 extends Object declared in method <T#2>toList()
  where CAP#1,CAP#2,CAP#3,CAP#4 are fresh type-variables:
    CAP#1 extends Object from capture of ?
    CAP#2 extends E from capture of ? extends E
    CAP#3 extends Object from capture of ?
    CAP#4 extends Object from capture of ?
1 error