springboot SearchStrategy of ConditionalOnSingleCandidate annotation only consider SearchStrategy.ALL

When I was browsing the source code, I found that OnBeanCondition.class on ConditionalOnSingleCandidate annotation, match the singleAutowireCandidate method only consider SearchStrategy of SearchStrategy.ALL. Line number is: 143.

the original source code was this:

else if (!hasSingleAutowireCandidate(context.getBeanFactory(),
        matchResult.getNamesOfAllMatches(),
        spec.getStrategy() == SearchStrategy.ALL)) {
    return ConditionOutcome.noMatch(ConditionMessage
            .forCondition(ConditionalOnSingleCandidate.class, spec)
            .didNotFind("a primary bean from beans")
            .items(Style.QUOTE, matchResult.getNamesOfAllMatches()));
}

I wonder why we don't consider two other strategies here。

Comment From: philwebb

It's not so clear from the formatting, but the spec.getStrategy() == SearchStrategy.ALL is not part of the if. It's actually the third argument to hasSingleAutowireCandidate (named considerHierarchy).

So all it's saying is if spec.getStrategy() == SearchStrategy.ALL then we will search the full application context hierarchy, otherwise we just search the current application context.