### Question:
HMapIL implements MapIL, Cloneable, Serializable { @Override public void plus(MapIL m) { for (MapIL.Entry e : m.entrySet()) { int key = e.getKey(); if (this.containsKey(key)) { this.put(key, this.get(key) + e.getValue()); } else { this.put(key, e.getValue()); } } } HMapIL(int initialCapacity, float loadFactor);  HMapIL(int initialCapacity);  HMapIL();  HMapIL(MapIL m); @Override int size(); @Override boolean isEmpty(); @Override long get(int key); @Override boolean containsKey(int key); @Override long put(int key, long value); @Override void putAll(MapIL m); @Override long remove(int key); @Override void clear(); @Override boolean containsValue(long value); @Override Object clone(); @Override Set<Integer> keySet(); @Override Collection<Long> values(); @Override Set<MapIL.Entry> entrySet(); @Override String toString(); @Override void plus(MapIL m); @Override long dot(MapIL m); @Override void increment(int key); @Override void increment(int key, long value); MapIL.Entry[] getEntriesSortedByValue(); MapIL.Entry[] getEntriesSortedByValue(int n);  }### Answer:
@Test public void testPlus() throws IOException { HMapIL m1 = new HMapIL(); m1.put(1, Integer.MAX_VALUE + 5L); m1.put(2, Integer.MAX_VALUE + 22L); m1.put(Integer.MAX_VALUE, Integer.MAX_VALUE); HMapIL m2 = new HMapIL(); m2.put(1, 4L); m2.put(3, Integer.MAX_VALUE + 5L); m2.put(Integer.MAX_VALUE, Integer.MAX_VALUE); m1.plus(m2); assertEquals(m1.size(), 4); assertTrue(m1.get(1) == Integer.MAX_VALUE + 9L); assertTrue(m1.get(2) == Integer.MAX_VALUE + 22L); assertTrue(m1.get(3) == Integer.MAX_VALUE + 5L); assertTrue(m1.get(Integer.MAX_VALUE) == 2L * Integer.MAX_VALUE); }