Path extension takes precedence over Accept Header (#454)

We have many users some access the API through their web browsers. They
often wish to download a CSV file and use a link with a path extension
(.csv for example) in their web browser.

A web browser always sends its own Accept header, which includes at
least `application/xml`. Since this takes precedence, the user is
returned XML, instead of the CSV they wanted.

By changing the order of the ContentNegotiation strategies we make sure
the path extension takes precedence.

Author: mmwinther

klass-api/src/main/java/no/ssb/klass/api/config/WebConfiguration.java

@@ -36,7 +36,6 @@ public void configurePathMatch(PathMatchConfigurer configurer) {
     public void configureContentNegotiation(ContentNegotiationConfigurer configurer) {
         configurer.strategies(
                 List.of(
-                        new HeaderContentNegotiationStrategy(),
                         new PathExtensionContentNegotiationStrategy(
                                 // Only these path extensions are allowed.
                                 Map.of(
@@ -45,6 +44,7 @@ public void configureContentNegotiation(ContentNegotiationConfigurer configurer)
                                         "json",
                                         MediaType.APPLICATION_JSON,
                                         "xml",
-                                        MediaType.APPLICATION_XML))));
+                                        MediaType.APPLICATION_XML)),
+                        new HeaderContentNegotiationStrategy()));
     }
 }

klass-api/src/test/java/no/ssb/klass/api/applicationtest/RestApiTechnicalDetailsTest.java

@@ -71,9 +71,10 @@ private static Stream<Arguments> validPathExtensionContentTypes() {
 
     @ParameterizedTest
     @MethodSource("validPathExtensionContentTypes")
-    void pathExtensionContentNegotiation(String pathExtension, String expectedContentType) {
+    void pathExtensionContentNegotiationTakesPrecedenceOverAcceptHeader(
+            String pathExtension, String expectedContentType) {
         given().port(port)
-                .noContentType() // Make sure the path extension is the sole specifier
+                .contentType(ContentType.XML)
                 .param("from", "2014-01-01")
                 .param("to", "2015-01-01")
                 .when()