The inference of Eclipse fails where javac works when using Collectors.teeing()

Hello, my code golf version of the Advent of Code 2023 Day 22 does not compile with Eclipse.

At some point in the code, Eclipse infers Object instead of the right type. "Type mismatch: cannot convert from Object to int" at line 35

I was not able to reduce the code to a smaller one :(

import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import java.util.TreeMap;
import java.util.stream.Collectors;
import java.util.stream.Gatherer;
import java.util.stream.Stream;

import static java.util.stream.Collectors.filtering;
import static java.util.stream.Collectors.flatMapping;
import static java.util.stream.Collectors.groupingBy;
import static java.util.stream.Collectors.mapping;
import static java.util.stream.Collectors.teeing;
import static java.util.stream.Collectors.toList;
import static java.util.stream.Collectors.toMap;
import static java.util.stream.Collectors.toSet;
import static java.util.stream.IntStream.rangeClosed;

public class AdventOfCode22 {
  record Pos(int x, int y) {}
  record Brick(int x1, int x2, int y1, int y2, int z1, int z2) {
    Stream<Pos> positions() {
      return x1 == x2 ? rangeClosed(y1, y2).mapToObj(y -> new Pos(x1, y)) :
          rangeClosed(x1, x2).mapToObj(x -> new Pos(x, y1));
    }
  }
  record Level(Brick brick, int z) {}
  record Pair<U,V>(U u, V v) { }

  static int numberOfBrickWithChildrenWithAtLeastTwoParents(String input) {
    var grid = new HashMap<Pos, Level>();
    return input.lines()
        .map(l -> {
          var array = Arrays.stream(l.split(",|~")).mapToInt(Integer::parseInt).toArray();
          return new Brick(array[0], array[3], array[1], array[4], array[2], array[5]);
        })
        .collect(groupingBy(Brick::z1, TreeMap::new, toList()))
        .values().stream()
        .flatMap(List::stream)
        .map(brick -> {
          var onTop = brick.positions()
              .map(pos -> grid.getOrDefault(pos, new Level(null, 0)))
              .collect(groupingBy(Level::z, TreeMap::new, flatMapping(l -> Stream.ofNullable(l.brick), toSet())))
              .lastEntry();
          var level =  new Level(brick, 1 + brick.z2 - brick.z1 + onTop.getKey());
          brick.positions().forEach(pos -> grid.put(pos, level));
          return new Pair<>(brick, onTop.getValue());
        })
        .collect(teeing(
            toMap(Pair::u, pair -> pair.v().size()),
            flatMapping(pair -> pair.v().stream().map(b -> new Pair<>(b, pair.u())),
                groupingBy(Pair::u, mapping(Pair::v, toList()))),
            (parentMap, childrenMap) ->
                (int) parentMap.keySet().stream()
                    .filter(parent -> childrenMap.getOrDefault(parent, List.of()).stream()
                        .allMatch(child -> parentMap.get(child) > 1))
                    .count()
        ));
  }

  public static void main(String[] args) {
    var input = """
        1,0,1~1,2,1
        0,0,2~2,0,2
        0,2,3~2,2,3
        0,0,4~0,2,4
        2,0,5~2,2,5
        0,1,6~2,1,6
        1,1,8~1,1,9
        """;
    System.out.println(numberOfBrickWithChildrenWithAtLeastTwoParents(input));
  }
}

eclipse-jdt / eclipse.jdt.core

The inference of Eclipse fails where javac works when using Collectors.teeing() #1789