[jira] [Created] (CAMEL-25547) camel-knative-http - a header with several values (a List or an array, such as a repeated request header) is sent as one header with the value "[a, b]", and the reply of the consumer sends only its last value

["shashank (Jira)" <ji...@apache.org>]

shashank created CAMEL-25547:
--------------------------------

             Summary: camel-knative-http - a header with several values (a List or an array, such as a repeated request header) is sent as one header with the value "[a, b]", and the reply of the consumer sends only its last value
                 Key: CAMEL-25547
                 URL: https://issues.apache.org/jira/browse/CAMEL-25547
             Project: Camel
          Issue Type: Bug
          Components: camel-knative-http
            Reporter: shashank
            Assignee: shashank


{{KnativeHttpProducer.process}} (lines 105-109 at main 9432ba16d026) copies each message header to the request with {{toString()}}:

{code:java}
for (Map.Entry<String, Object> entry : exchange.getMessage().getHeaders().entrySet()) {
    if (!headerFilterStrategy.applyFilterToCamelHeaders(entry.getKey(), entry.getValue(), exchange)) {
        headers.add(entry.getKey(), entry.getValue().toString());
    }
}
{code}

For a header whose value is a collection this is the {{toString()}} of the collection, so {{List.of("a", "b")}} is sent as the single header line {{X-Test: [a, b]}}, and a {{String[]}} as {{[Ljava.lang.String;@7112ce6}}. The Knative HTTP consumer itself maps a request header that occurs more than once to a List ({{CollectionHelper.appendEntry}} in {{KnativeHttpConsumer.toMessage}}), and so do the other HTTP consumers, so a route that forwards such a request to a Knative sink ({{from("knative:channel/in").to("knative:endpoint/out")}}) sends corrupted header values, without any error.

The reply of the consumer has a related defect. {{KnativeHttpConsumer.toHttpResponse}} (lines 331-344) iterates the values of a header, but calls {{response.putHeader(key, headerValue)}} for each of them, and {{putHeader}} replaces the header. A reply header with the values {{a}} and {{b}} is sent as {{X-Test: b}} only.

camel-http ({{HttpProducer}}), camel-netty-http and camel-undertow iterate the values with {{ObjectHelper.createIterator(value, null, true)}} and {{HttpUtil.applyHeader}} and send one header line per value, and a String as one value.

h3. Reproduction

New {{KnativeHttpMultiValueHeaderTest}} (the test HTTP server and the platform-http setup of the existing {{KnativeHttpTest}}): a message with the header {{X-Test}} as a List, as an array, and as a List with a null element is sent to a Knative sink, and the values of the header in the received request are compared; a consumer route sets the header to a List and the values of the reply header are compared; the same with a {{byte[]}} header for both. A seventh test (a String with a comma stays one value) passes on main too. On main, twice:
{noformat}
producerSendsEachValueOfAListHeader:        Expecting actual: ["[a, b]"] to contain exactly (and in same order): ["a", "b"]
producerSkipsTheMissingValuesOfAListHeader: Expecting actual: ["[a, null, b]"] to contain exactly (and in same order): ["a", "b"]
producerSendsEachValueOfAnArrayHeader:      Expecting actual: ["[Ljava.lang.String;@..."] to contain exactly (and in same order): ["a", "b"]
consumerRepliesWithEachValueOfAListHeader:  Expecting actual: ["b"] to contain exactly (and in same order): ["a", "b"]
producerSendsAByteArrayHeaderAsOneValue:    Expecting actual: ["[B@1dc9f5ad"] to contain exactly (and in same order): ["abc"]
consumerRepliesWithAByteArrayHeaderAsOneValue: Expecting actual: ["99"] to contain exactly (and in same order): ["abc"]
{noformat}

h3. Proposed fix

Both places use the same value handling as the CAMEL-25526 fix: a value that is an {{Iterable}} or an {{Object[]}} is iterated as camel-http does ({{ObjectHelper.createIterator}} without a delimiter and {{HttpUtil.applyHeader}}, which applies the header filter per value and skips null values) and all the values of the header are added at once. Every other value is one header, converted to a String with the type converter: a String (also one with commas) is sent as before; a {{byte[]}} is now sent as one String (the producer sent its {{toString()}}, {{[B@...}}, and the reply only its last byte as a number). A header with a null value is not sent, as before (the header filter drops it). 4.23 upgrade guide note added to the existing camel-knative section. camel-knative-http with the fix: 183 tests, 0 failures.

Not changed here: {{KnativeHttpProducer}} keeps only the last value of a response header that occurs more than once ({{answer.setHeader}} per entry); that is the opposite direction and would change the type of such a header for existing routes, so it is left for a separate decision.

Found by comparing the producer with its sibling in camel-vertx-http (CAMEL-25526), with a small Lean 4 model of the header copy: "a header is sent as one line per value" (camel-http) fails for {{["a", "b"]}} in the producer (one line {{[a, b]}}) and in the reply (only {{b}}); the producer is proved wrong for every list value and the reply for every list of two or more values, and the fix is proved to equal camel-http's behaviour for every value and to send the same line as before for every String. Confirmed with the real producer and consumer.

Affected: main, camel-4.22.x, camel-4.18.x, camel-4.14.x (same code in both classes, GitHub contents API).

Duplicate check (2026-10-11): JIRA text "knative" and "header" since 2024 (14; CAMEL-24084 and CAMEL-24803 are about the header filter and the header metadata, CAMEL-25526 is the camel-vertx-http ticket); GitHub open pull requests with "knative" in the title: none. No open pull request changes {{KnativeHttpProducer}} or {{KnativeHttpConsumer}}.

_Filed with Claude Code on behalf of allthingssecurity._




--
This message was sent by Atlassian Jira
(v8.20.10#820010)