Spring 4.3's HeaderContentNegotiationStrategy switched from looking up the Accept header via the method returning a single (potentially comma separated) one to the method returning multiple headers in the first place. We now added an override of HttpServletRequestWrapper.getHeaders(…) to out custom adapter defaulting the media type to make sure the defaulting is visible and thus the right handler methods are looked up.
That previously missing caused the DelegatingHandlerMapping selecting the redirect to the HAL browser in case a request to the API root was sent without an accept header as the defaulting of the header to application/hal+json wasn't properly exposed anymore and the redirect to the browser — declaring a produces clause of text/html — was not causing any media type mismatch anymore.
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