Add more HttpHeaders constants for standard HTTP headers [SPR-12063]

[spring-projects-issues]

Artem Bilan opened SPR-12063 and commented

See the linked issue (INT-3488) and its PR

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Issue Links:

• INT-3488 HTTP Inbound Gateway headers not mapping Content-Disposition ("is depended on by")
• Make constants in HttpHeaders public [SPR-11749] #16371 Make constants in HttpHeaders public

Referenced from: commits ebc5fea