code: @Test public void testGrowing(){
    final HeaderMap headerMap=new HeaderMap();
    for (  HttpString item : HTTP_STRING_LIST) {
      for (int i=0; i < (item.hashCode() & 7) + 1; i++)     headerMap.add(item,"Test value");
    }
    for (  HttpString item : HTTP_STRING_LIST) {
      assertTrue(String.format("Missing %s (hash %08x)",item,Integer.valueOf(item.hashCode())),headerMap.contains(item));
      assertNotNull(headerMap.get(item));
      assertEquals((item.hashCode() & 7) + 1,headerMap.get(item).size());
      assertEquals("Test value",headerMap.getFirst(item));
      assertEquals("Test value",headerMap.getLast(item));
    }
    assertEquals(HTTP_STRING_LIST.size(),headerMap.size());
    for (  HttpString item : HTTP_STRING_LIST) {
      assertTrue(headerMap.contains(item));
      assertNotNull(headerMap.remove(item));
      assertFalse(headerMap.contains(item));
    }
    assertEquals(0,headerMap.size());
  }
  