Differentiate "Session not found" from a regular HTTP 404 response

[YunKuiLu]

java-sdk/mcp-spring/mcp-spring-webflux/src/main/java/io/modelcontextprotocol/client/transport/WebClientStreamableHttpTransport.java

Lines 204 to 207 in c3a0b18

	else if (isNotFound(response)) {
	String sessionIdRepresentation = sessionIdOrPlaceholder(transportSession);
	return mcpSessionNotFoundError(sessionIdRepresentation);
	}

It currently shows "Session not found" even when the HTTP endpoint doesn't exist, which can be misleading for developers.

[chemicL]

Has this not been fixed in #469?

[YunKuiLu]

@chemicL Sorry I didn’t see the message while on vacation. I will review the issue again and close it if there are no problems. Thank you for your contributions.