I reproduced with 9-ea+164, and it occurs at least as far back as 9-ea+95.

===
import java.util.Map;
import java.util.concurrent.ExecutorService;
import java.util.function.*;
import java.util.stream.*;

abstract class X {
  public interface N<K, V> {}

  abstract <K, V> N<K, V> c();

  abstract <T, K, V, M extends N<K, V>> Collector<T, ?, M> f(
      Function<? super T, ? extends K> k,
      Function<? super T, ? extends Stream<? extends V>> v,
      Supplier<M> multimapSupplier);

  void m(Map<String, N<?, ?>> c, ExecutorService s) {
    s.submit(() -> {
        return c.entrySet().parallelStream()
            .collect(f(Map.Entry::getKey, e -> e.getValue().getValues(), this::c));
    });
  }
}
===

$ javac X.java
java.lang.NullPointerException
        at jdk.compiler/com.sun.tools.javac.comp.Infer$CheckUpperBounds.apply(Infer.java:951)
        at jdk.compiler/com.sun.tools.javac.comp.Infer.doIncorporation(Infer.java:1122)
        at jdk.compiler/com.sun.tools.javac.comp.Infer$GraphSolver.solve(Infer.java:1658)
        at jdk.compiler/com.sun.tools.javac.comp.InferenceContext.solve(InferenceContext.java:475)
        at jdk.compiler/com.sun.tools.javac.comp.InferenceContext.solve(InferenceContext.java:482)
        at jdk.compiler/com.sun.tools.javac.comp.Infer$PartiallyInferredMethodType.check(Infer.java:341)
        at jdk.compiler/com.sun.tools.javac.comp.ArgumentAttr$ResolvedMemberType.overloadCheck(ArgumentAttr.java:565)