To think: maybe it will be better to get a bean `IntegrationEvaluationContextFactoryBean` from parent context and inherit EC components from there?..
There reason: working under `@SpelFunction` leads me to the issue, when I can't inherit functions from parent context, because `IntegrationEvaluationContextFactoryBean#afterPropertiesSet()` works earlier, than `SpelFunctionAnnotationPostProcessor#postProcessBeforeInitialization`