[BUG] ModifyResponse replaceHeaderKeys changes header value instead of header name #6510

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• I had searched in the issues and found no similar issues.

Apache ShenYu Component

shenyu-plugin

What happened

ModifyResponseRuleHandle.replaceHeaderKeys is documented as a header-name replacement map:

/**
 * replace header map
 * key: oldHeaderKey, value: newHeaderKey.
 */
private Map<String, String> replaceHeaderKeys;

But ModifyResponsePlugin applies the map like this:

if (MapUtils.isNotEmpty(this.ruleHandle.getReplaceHeaderKeys())) {
    Map<String, String> replaceHeaderMap = this.ruleHandle.getReplaceHeaderKeys();
    replaceHeaderMap.forEach((key, value) -> httpHeaders.replace(key, Collections.singletonList(value)));
}

HttpHeaders.replace(key, values) keeps the same header key and replaces its values. Therefore a rule such as:

{
  "replaceHeaderKeys": {
    "X-Old": "X-New"
  }
}

will return:

X-Old: X-New

instead of renaming the header to:

X-New: <original X-Old values>

Expected behavior

replaceHeaderKeys should rename response header keys according to the documented oldHeaderKey -> newHeaderKey mapping while preserving the original header values, or the field should be renamed/re-documented if the intended behavior is value replacement. The current implementation does neither and produces incorrect response headers.

How to reproduce

1. Enable the modify-response plugin.
2. Configure a rule with replaceHeaderKeys mapping X-Old to X-New.
3. Let the upstream return X-Old: abc.
4. The gateway returns X-Old: X-New instead of X-New: abc.

Debug logs

No response

Environment

Current master branch.

Are you willing to submit a PR?

• Yes I am willing to submit a PR!