final Map<String, String> headerMap = new HashMap<>();
        provider.adjustActionResponseHeaders("application/xml", (k, v) -> headerMap.put(k, v));
        assertEquals(2, headerMap.size());
        assertEquals("def", headerMap.get("X-Def"));
        assertEquals("def2", headerMap.get("X-Def2"));
    }

    @Test

        "cache-control",
        "no-cache",
        "cache-control",
        "no-store",
        "user-agent",
        "OkHttp",
      )
    val headerMap = headers.toMultimap()
    assertThat(headerMap["cache-control"]!!.size).isEqualTo(2)
    assertThat(headerMap["user-agent"]!!.size).isEqualTo(1)
  }

  @Test fun toMultimapUsesCanonicalCase() {
    val headers =
      Headers.headersOf(
        "cache-control",

        sourceMap.put("searchField", searchFieldMap);
        final Map<String, List<String>> headerMap = headerList.stream()
                .collect(Collectors.groupingBy(Pair::getFirst, Collectors.mapping(Pair::getSecond, Collectors.toList())));
        sourceMap.put("headers", headerMap);
        sourceMap.put("documents", documentList);
        return sourceMap;
    }

    @Override

	// Get header map.
	headerMap := make(map[string][]string)
	for k, vv := range req.Header {
		// If request header key is not in ignored headers, then add it.
		if _, ok := ignoredStreamingHeaders[http.CanonicalHeaderKey(k)]; !ok {
			headerMap[strings.ToLower(k)] = vv
		}
	}

	// Get header keys.
	headers := []string{"host"}
	for k := range headerMap {
		headers = append(headers, k)
	}

	}

	return opts, valid
}

func parseObjectAttributes(h http.Header) (attributes map[string]struct{}) {
	attributes = make(map[string]struct{})
	for _, headerVal := range h.Values(xhttp.AmzObjectAttributes) {
		for v := range strings.SplitSeq(strings.TrimSpace(headerVal), ",") {
			if v != "" {
				attributes[v] = struct{}{}
			}
		}
	}

	return attributes
}