About UriComponentsBuilder and UriComponents

UriComponentsBuilder b1 = UriComponentsBuilder.fromHttpUrl("https://www.example.com/hotels/42?filter=f1&filter=f2&option&query=#hash");
UriComponents c1 = b1.build();
assertEquals("https", c1.getScheme());
assertEquals("www.example.com", c1.getHost());
assertEquals(-1, c1.getPort());
assertEquals(Lists.list("hotels", "42"), c1.getPathSegments());
assertEquals("f1", c1.getQueryParams().getFirst("filter"));
assertNull(c1.getQueryParams().getFirst("option"));
assertEquals("", c1.getQueryParams().getFirst("query"));
assertEquals("hash", c1.getFragment());

UriComponentsBuilder b2 = b1.cloneBuilder();
b2.path("/info");
assertEquals("https://www.example.com/hotels/42/info?filter=f1&filter=f2&option&query=#hash", b2.build().toUriString());

UriComponentsBuilder b3 = b1.cloneBuilder();
b3.replacePath("/info/hotels/42");
assertEquals("https://www.example.com/info/hotels/42?filter=f1&filter=f2&option&query=#hash", b3.build().toUriString());

UriComponentsBuilder b4 = b1.cloneBuilder();
b4.replaceQuery(null);
b4.fragment(null);
b4.userInfo("user1");
assertEquals("https://user1@www.example.com/hotels/42", b4.build().toUriString());

UriComponentsBuilder b5 = b1.cloneBuilder();
b5.queryParam("query", "q1", "q2");
assertEquals("https://www.example.com/hotels/42?filter=f1&filter=f2&option&query=&query=q1&query=q2#hash", b5.build().toUriString());

UriComponentsBuilder b6 = b1.cloneBuilder();
b6.replaceQueryParam("query", "q1", "q2");
assertEquals("https://www.example.com/hotels/42?filter=f1&filter=f2&option&query=q1&query=q2#hash", b6.build().toUriString());

assertEquals("/hotels/42?filter=hot&cold", UriComponentsBuilder.fromUriString("/hotels/42").query("filter={value}").buildAndExpand(Collections.singletonMap("value", "hot&cold")).toUriString());