RFC 6455 4.2.1.4 case sensitivity fix
RFC 6455 4.2.1.4 case sensitivity fix

This is a case sensitivity fix for the Connection header Upgrade value to make this part meet the requirement of IETF websocket RFC 6455 4.2.1.4: "A |Connection| header field that includes the token "Upgrade", treated as an ASCII case-insensitive value."
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