Provide first-class configuration support for SpEL `IndexAccessor`

[sbrannen]

Overview

As mentioned in #9429 (comment), Spring Integration currently provides first-class support for registering a PropertyAccessor but not yet for an IndexAccessor (new SpEL API introduced in Spring Framework 6.2).

For example, one can currently register a PropertyAccessor for use with Spring Integration via the following.

1. IntegrationEvaluationContextFactoryBean and IntegrationSimpleEvaluationContextFactoryBean
2. the <spel-property-accessors> XML namespace element
3. a SpelPropertyAccessorRegistrar bean in the ApplicationContext.

However, there is currently no easy way for Spring Integration users to register an IndexAccessor (either a custom one of their own or the JsonIndexAccessor proposed in #9429).

Thus, the Spring Integration team should decide if it wants to provide similar configuration support for registering an IndexAccessor:

• via AbstractEvaluationContextFactoryBean and its subclasses
• via an XML namespace element
• via an auto-detected bean in the ApplicationContext -- SpelPropertyAccessorRegistrar or a separate SpelIndexAccessorRegistrar

Side Note

IntegrationSimpleEvaluationContextFactoryBean is not currently documented in the reference manual. If that warrants documentation, a new issue can be created to address that.

Related Issues

• Introduce JsonIndexAccessor #9383
• Introduce JsonIndexAccessor #9429

[artembilan]

Hi @sbrannen !
FYI: #9451
Thanks