static <T> ContextAwareCallable<T> of(RequestContext context, Callable<T> callable) {
        return new DefaultContextAwareCallable<T>(context, callable);
    }
Returns a new {@link ContextAwareCallable} that sets the specified {@link RequestContext}
before executing an underlying {@link Callable}.
core/src/main/java/com/linecorp/armeria/common/ContextAwareCallable.java