@Test
public void testGetStringCollection() {

  Configuration c = new Configuration();
  c.set("x", " a, b\n,\nc ");
  Collection<String> strs = c.getTrimmedStringCollection("x");
  assertEquals(3, strs.size());
  assertArrayEquals(new String[]{ "a", "b", "c" },
      strs.toArray(new String[0]));
  // Check that the result is mutable
  strs.add("z");
  // Make sure same is true for missing config
  strs = c.getStringCollection("does-not-exist");
  assertEquals(0, strs.size());
  strs.add("z");
}