Fix the baseUrl is configured with a trailing slash #645

[leehaut]

Fixes #645

Replace unsafe string concatenation with UriComponentsBuilder to build a normalized, valid URL:

UriComponentsBuilder.fromHttpUrl(baseUrl)
    .path(messageEndpoint)
    .queryParam("sessionId", sessionId)
    .build()
    .toUriString();

Testing

• Verified with baseUrl=http://localhost:8080/ → correct URL
• Verified with baseUrl=http://localhost:8080 → correct URL
• Integration test added to assert URL format

[Kehrlann]

Hey @leehaut ! Thanks for your contribution. Could you please apply the same to:

• WebFluxSseServerTransportProvider
• HttpServletSseServerTransportProvider

[Kehrlann]

Nitpick: / is not a valid context path, please null or "".

[Kehrlann]

Use 2025

[leehaut]

Thanks! I've updated both WebFluxSseServerTransportProvider and HttpServletSseServerTransportProvider accordingly. Let me know if you need any further changes.

[Kehrlann]

Sorry this comes a bit late, but I'm reluctant to add 300 lines of URL-handling code for what amounts to removing a trailing slash on a string.

Please remove the URI builder, and instead introduce a static method in the transports for trimming the slash:

if (u.endsWith("/")) {
    return u.substring(0, s.length() - 1);
}

It doesn't handle everything but we don't want to sanitize any possible user configuration.

[Kehrlann]

Let's put this comment on a single line above, above the code

[Kehrlann]

Thank you for your contribution.