This commit adds callouts to two sets of Java/Kotlin code examples in
the @ModelAttribute section for Web MVC in order to work around the
"Code example has callout from a different code example" bug.
This also aligns the Web MVC examples with the WebFlux examples.
As a side note, the bug can also be seen in the WebFlux documentation
if the callouts are removed from the first Java/Kotlin examples in the
@ModelAttribute section for WebFlux. Thus it appears to be a general
issue related to examples within a given section of the documentation
when some examples have callouts and others do not, likely due to a bug
in the Javascript that provides this feature.
See gh-29505
ac7d428a62