Type arg inference false positive because of qualifiers

[smillst]

import java.util.LinkedHashMap;
import java.util.Map;
import java.util.function.BinaryOperator;
import java.util.function.Function;
import java.util.stream.Collector;
import java.util.stream.Stream;
import org.checkerframework.checker.interning.qual.Interned;

public class InterningError {

  void method(Stream<Integer> integerStream) {
    LinkedHashMap<Integer, Integer> c = integerStream.collect(
        toMap(Function.identity(), v -> 1, InterningError::sum));
  }

  public static <T, K, U, M extends Map<K, U>> Collector<T, ?, M> toMap(
      Function<? super T, ? extends K> keyMapper, Function<? super T, ? extends U> valueMapper,
      BinaryOperator<U> mergeFunction) {
    throw new RuntimeException();
  }

  static @Interned Integer sum(Integer a, Integer b) {
    return a + b;
  }

}

Produces the following false positive with the Interning Checker:

InterningError.java:12: error: [type.arguments.not.inferred] Could not infer type arguments for Stream.collect
    LinkedHashMap<Integer, Integer> c = integerStream.collect(
                                                             ^
  unsatisfiable constraint: LinkedHashMap<Integer, Integer> <: Map<Integer, @Interned Integer>
1 error

Inference should be able to correctly infer the type arguments in this case. I think there's a bug in the qualifier constraints some where.