refactor: remove unreachable null check per Copilot suggestion

Remove the null check for allowedHost since isAllowedUrl() validation
guarantees the canonicalized host exists in CANONICALIZED_TO_ORIGINAL map.
The check was technically unreachable code.

This simplifies the code while maintaining the same security guarantees.

Author: DerekRoberts

backend-java/.mvn/wrapper/MavenWrapperDownloader.java

@@ -192,11 +192,6 @@ private static void downloadFileFromURL( URL wrapperUrl, Path wrapperJarPath )
         String canonicalizedHost = canonicalizeHost(wrapperUrl.getHost());
         String allowedHost = CANONICALIZED_TO_ORIGINAL.get(canonicalizedHost);
 
-        // This should never be null given the validation above, but kept as a safety check
-        if (allowedHost == null) {
-            throw new IOException("URL validation failed: Host validation error.");
-        }
-        
         // Construct URL using whitelist host (not user-provided host) and default port
         // Always use -1 to ensure default HTTPS port (443) is used
         // This ensures CodeQL recognizes we're using sanitized data