Optional autowire of Map<String, BeanType> accidentally falls back to unrelated Map<String, String> [SPR-13963]

[spring-projects-issues]

Phil Webb opened SPR-13963 and commented

Upgrading Spring Boot to Framework to 4.3is not currently possible due to failure in EndpointAutoConfigurationTests.

It appears that this line in EndpointAutoConfiguration:

@Autowired(required = false)
private Map<String, HealthIndicator> healthIndicators = new HashMap<String, HealthIndicator>();

No longer works correctly as String values end up in the map.

I believe that commit 3f74a74481d is ultimately responsible as rolling this back seems to fix the issue.

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Affects: 4.3 RC1

Issue Links:

• Allow for normal bean wiring semantics for types assignable to Map [SPR-7915] #12570 Allow for normal bean wiring semantics for types assignable to Map
• Self reference fallback in 4.3 is not meant to apply to collection elements [SPR-14965] #19532 Self reference fallback in 4.3 is not meant to apply to collection elements
• Can't autowire BiMap: container resolves non-matching Map of value beans [SPR-15117] #19684 Can't autowire BiMap: container resolves non-matching Map of value beans

Referenced from: commits 48ee9b5, 1b53edf

[spring-projects-issues]

Juergen Hoeller commented

We're explicitly excluding Collection and Map beans from fallback matching now. They are being treated specifically for autowiring purposes in general, so it's not out of the ordinary to handle them specifically here as well.

However, this also means that Collection and Map beans never match unless they qualify as a full generic type match. This is easy enough to accomplish with factory methods with a specifically declared return type... but hard with a regular XML bean definition. I'm not too concerned though since this feature is not primarily about plain value holder collections; it's rather about implementations beans which happen to implement Collection / Map as well. Arbitrary Collection and Map beans can still be injected using @Resource, as before.

Juergen