### Question:
HeaderSource { public static HeaderSource of(String headerPath, String encoding, ResourceFinder finder) { return of(null, encoding, finder); } HeaderSource(String content, boolean inline); static HeaderSource of(String headerPath, String encoding, ResourceFinder finder); static HeaderSource of(Multi multi, String inlineHeader, String headerPath, String encoding, ResourceFinder finder); String getContent(); boolean isInline(); abstract boolean isFromUrl(URL location);  }### Answer:
@Test(expected=IllegalArgumentException.class) public void testOfNulls() { HeaderSource.of(null, null, null, "utf-8", finder); }
@Test(expected=IllegalArgumentException.class) public void testOfEmptyAndNull() { HeaderSource.of(null, "", null, "utf-8", finder); }
@Test(expected=IllegalArgumentException.class) public void testOfMultiNulls() { HeaderSource.of(new Multi(), null, null, "utf-8", finder); }
@Test(expected=IllegalArgumentException.class) public void testOfMultiEmptyAndNull() { final Multi multi = new Multi(); multi.setInlineHeaders(new String[0]); HeaderSource.of(multi, "", null, "utf-8", finder); }