Log a warning if param not annotated with @ProjectedPayload

[onobc]

This commit introduces a warning log if a parameter is not annotated with @ProjectedPayload that this style is deprecated and that we will drop support for projections if a parameter is not annotated with @ProjectedPayload.

Resolves #3300

The output log message looks as follows:

2025-05-29 15:20:58,924 WARN eb.ProxyingHandlerMethodArgumentResolver: 271 - Parameter (method 'withModelAttribute' parameter 0) is not annotated with @ProjectedPayload - support for parameters not explicitly annotated with @ProjectedPayload (at the parameter or type level) will be dropped in a future version.

Note

If the parameter actually has a name (MethodParameter.getName() != null) then it will be included just before (method 'withModelAttribute' parameter...

• You have read the Spring Data contribution guidelines.
• You use the code formatters provided here and have them applied to your changes. Don’t submit any formatting related changes.
• You submit test cases (unit or integration tests) that back your changes.
• You added yourself as author in the headers of the classes you touched. Amend the date range in the Apache license header if needed. For new types, add the license header (copy from another file and set the current year only).

[onobc]

My spidey-senses are typically activated when I add a map of things that could ultimately grow unbounded and OOME if something went awry. That would lead me to use the ConcurrentLruCache from framework. However, the added complexity plus the LruCache get API has no signal as to whether the cache was originally empty (this is the signal I needed). I chose simplicity over paranoia here.

What is the biggest number of method params we have encountered in the wilderness via bug reports etc..???

IOW - you good w/ this?

[odrotbohm]

Does it make sense to switch to a simple static boolean? I guess a single warning is just enough. That would reduce this to a Logger declaration in ProxyingHandlerMethodArgumentResolver and a simple if?

[onobc]

The thinking behind logging per parameter is that the user will get a more directly actionable message. Otherwise they may end up doing wak-a-mole to find the problematic parameter.

[onobc]

I updated the PR to include more context/location in the log message. It now looks like:

2025-06-02 11:18:57,706 WARN eb.ProxyingHandlerMethodArgumentResolver: 271 - Parameter 'foo' at position 0 in org.springframework.data.web.ProxyingHandlerMethodArgumentResolverUnitTests$Controller.withModelAttribute is not annotated with @ProjectedPayload - support for parameters not explicitly annotated with @ProjectedPayload (at the parameter or type level) will be dropped in a future version.