MockHttpServletResponse - handle multiple values for Content-Language header

[Romster]

Affects: 6.x+

It seems that if we provide multiple values for CONTENT_LANGUAGE as an array like:

ResponseEntity.ok()
      .header(HttpHeaders.CONTENT_LANGUAGE, contentLanguage.toArray(new String[0]))
      .body(body);

It won't work nicely with MockHttpServletResponse.

The logic we have there in setSpecialHeader method:

spring-framework/spring-test/src/main/java/org/springframework/mock/web/MockHttpServletResponse.java

Lines 756 to 767 in 8b14bf8

	else if (HttpHeaders.CONTENT_LANGUAGE.equalsIgnoreCase(name)) {
	String contentLanguages = value.toString();
	HttpHeaders headers = new HttpHeaders();
	headers.add(HttpHeaders.CONTENT_LANGUAGE, contentLanguages);
	Locale language = headers.getContentLanguage();
	setLocale(language != null ? language : Locale.getDefault());
	// Since setLocale() sets the Content-Language header to the given
	// single Locale, we have to explicitly set the Content-Language header
	// to the user-provided value.
	doAddHeaderValue(HttpHeaders.CONTENT_LANGUAGE, contentLanguages, true);
	return true;
	}

expects that all the values are sent in a value.

but from debugging, I saw that ServletServerHttpResponse will call setSpecialHeader of MockHttpServletResponse for each header's value.

spring-framework/spring-web/src/main/java/org/springframework/http/server/ServletServerHttpResponse.java

Lines 113 to 119 in 8b14bf8

	private void writeHeaders() {
	if (!this.headersWritten) {
	getHeaders().forEach((headerName, headerValues) -> {
	for (String headerValue : headerValues) {
	this.servletResponse.addHeader(headerName, headerValue);
	}
	});

Thus, only the last value will be present in the response.

[bclozel]

Thanks for the report @Romster this has been fixed for the next set of maintenance releases.