Accept header ends with "," produces HTTP "406 Not Acceptable"

[j3r0lin]

Spring version: 5.1.8.RELEASE

Send a http request with header like this, containing , at the end.

Accept: application/json, 

HeaderContentNegotiationStrategy will produce a HttpMediaTypeNotAcceptableException exception.

org.springframework.web.HttpMediaTypeNotAcceptableException: Could not parse 'Accept' header [application/json,]: Invalid mime type "": 'mimeType' must not be empty
	at org.springframework.web.accept.HeaderContentNegotiationStrategy.resolveMediaTypes(HeaderContentNegotiationStrategy.java:59) ~[spring-web-5.1.8.RELEASE.jar!/:5.1.8.RELEASE]
	at org.springframework.web.accept.ContentNegotiationManager.resolveMediaTypes(ContentNegotiationManager.java:124) ~[spring-web-5.1.8.RELEASE.jar!/:5.1.8.RELEASE]
	at org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodProcessor.getAcceptableMediaTypes(AbstractMessageConverterMethodProcessor.java:391) ~[spring-webmvc-5.1.8.RELEASE.jar!/:5.1.8.RELEASE]
	at org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodProcessor.writeWithMessageConverters(AbstractMessageConverterMethodProcessor.java:229) ~[spring-webmvc-5.1.8.RELEASE.jar!/:5.1.8.RELEASE]
	at org.springframework.web.servlet.mvc.method.annotation.HttpEntityMethodProcessor.handleReturnValue(HttpEntityMethodProcessor.java:225) ~[spring-webmvc-5.1.8.RELEASE.jar!/:5.1.8.RELEASE]
	at org.springframework.web.method.support.HandlerMethodReturnValueHandlerComposite.handleReturnValue(HandlerMethodReturnValueHandlerComposite.java:82) ~[spring-web-5.1.8.RELEASE.jar!/:5.1.8.RELEASE]

That http request works before 5.1.2.RELEASE.
Maybe cause of this parsing method refactor in this commit f4b05dc
StringUtils.tokenizeToStringArray(mimeTypes, ",") will strim tokens and ignore empty tokens by default, but now, the replacement method not support that anymore.

[j3r0lin]

Wrong place, moved to spring-framework repo