Treat the only one default candidate as effectively primary

[Pankraz76]

Close spring-projectsGH-34432

[Pankraz76]

nice approach looks perfectly fine to me.

[Pankraz76]

well done

[Pankraz76]

maybe filtering would highlight the main condition:

.filter(entry -> entry.getValue().isAutowireCandidate() && entry.getValue().isDefaultCandidate())

protected String determineEffectivelyPrimaryCandidate(Map<String, Object> candidates, Class<?> requiredType) {
    return candidates.entrySet().stream()
        .map(entry -> Map.entry(entry.getKey(), transformedBeanName(entry.getKey())))
        .filter(entry -> containsBeanDefinition(entry.getValue()))
        .map(entry -> Map.entry(entry.getKey(), getMergedLocalBeanDefinition(entry.getValue())))
        .filter(entry -> entry.getValue().isAutowireCandidate() && entry.getValue().isDefaultCandidate())
        .map(Map.Entry::getKey)
        .reduce((a, b) -> null) // Ensures only one candidate; otherwise, null
        .orElse(null);
}

Its although nice, if a method has only has one return statement.