[wleeaf]

AssetHandler handles conditional requests in three ways that differ from RFC 9110.

1. If-None-Match is compared as one string. The field is * or a comma-separated list of entity tags, compared with the weak comparison function, so W/"x" and "x" match (section 13.1.2). Today these requests get a full 200 for an unchanged asset:
   • If-None-Match: "x", W/"<etag>"
   • If-None-Match: *
   • If-None-Match: "<etag>", the ETag without W/
2. If-Modified-Since is checked even when If-None-Match is present. Section 13.2.2 says it is only evaluated when the request has no If-None-Match. As a result, If-None-Match: "stale" together with the asset's own Last-Modified gets 304, and a cache keeps a response whose ETag the server no longer has. ETags are more precise than dates (one-second resolution), which is why they take precedence.
3. An If-Modified-Since that isn't a date is a 400. If-Modified-Since: yesterday throws TypeMismatchException from Value.longValue. Section 13.1.3 says the recipient must ignore a value that isn't a valid HTTP-date.

The change:

• Matches If-None-Match with a new etagMatches(): an exact match as before, or *, or a list element equal to the ETag once W/ is removed from both.
• Reads If-Modified-Since only when the request has no If-None-Match.
• Treats an unparseable If-Modified-Since as absent.

A 304 still has no ETag, as FeaturedTest expects.

The new AssetHandlerTest (Mockito, like the other handler tests) runs nine header combinations against a mocked Asset. Without the change, six of them fail: the strong form, both lists and * get 200, the stale tag plus date gets 304, and yesterday throws. mvn -pl jooby test passes (1307 tests), and spotless:check reports no violations in the changed files.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.19%. Comparing base (e64c771) to head (85238dc).

Additional details and impacted files

@@            Coverage Diff            @@
##               main    #4027   +/-   ##
=========================================
  Coverage     94.18%   94.19%           
- Complexity     6656     6665    +9     
=========================================
  Files           432      432           
  Lines         20897    20909   +12     
  Branches       2096     2099    +3     
=========================================
+ Hits          19682    19695   +13     
+ Misses          762      759    -3     
- Partials        453      455    +2     

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