PrefixTagLibraryResolver r3 = new MockPrefixTagLibraryResolver("jelly", t3);
TagLibraryResolver r3 = new MockTagLibraryResolver("jelly", t3);
    public void testAddTagLibraryResolver() {        ParserConfiguration p = new ParserConfiguration();        try {            p.addTagLibraryResolver(new MockPrefixTagLibraryResolver(null, null));            fail("added tag library resolver with null URI prefix");        } catch (NullPointerException e) {            // expected        }        try {            p.addTagLibraryResolver(new MockPrefixTagLibraryResolver("", null));            fail("added tag library resolver with empty URI prefix");        } catch (IllegalArgumentException e) {            // expected        }        try {            p.addTagLibraryResolver(null);            fail("added null tag library resolver");        } catch (NullPointerException e) {            // expected        }        TagLibrary t1 = new MockTagLibrary();        TagLibrary t2 = new MockTagLibrary();        PrefixTagLibraryResolver r1 = new MockPrefixTagLibraryResolver("prefix", t1);        PrefixTagLibraryResolver r2 = new MockPrefixTagLibraryResolver("prefix", t2);        assertNull(p.findTagLibrary("prefix:suffix"));        p.addTagLibraryResolver(r1);        assertEquals(t1, p.findTagLibrary("prefix:suffix"));        p.addTagLibraryResolver(r2);        assertEquals(t2, p.findTagLibrary("prefix:suffix"));        TagLibrary t3 = new MockTagLibrary();        PrefixTagLibraryResolver r3 = new MockPrefixTagLibraryResolver("jelly", t3);        assertNull(p.findTagLibrary("jelly:core"));        p.addTagLibraryResolver(r3);        assertEquals(t2, p.findTagLibrary("prefix:suffix"));        assertEquals(t3, p.findTagLibrary("jelly:core"));        assertNull(p.findTagLibrary("unregistered"));    }