Add an Access-Control-Request-Method check for CORS preflight requests [SPR-13193]

[spring-projects-issues]

Sébastien Deleuze opened SPR-13193 and commented

Since based on CORS specification the Access-Control-Request-Method request header is mandatory for preflight requests, we should add this check to CorsUtils.isPreFlightRequest() and FrameworkServlet.doOptions() to identify them more reliably.

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Referenced from: commits 8ee0e78