private static String computePathPrefix(Class<?> clazz, String pathPrefix) {
        ensureAbsolutePath(pathPrefix, "pathPrefix");
        final PathPrefix pathPrefixAnnotation = AnnotationUtil.findFirst(clazz, PathPrefix.class);
        if (pathPrefixAnnotation == null) {
            return pathPrefix;
        }
        final String pathPrefixFromAnnotation = pathPrefixAnnotation.value();
        ensureAbsolutePath(pathPrefixFromAnnotation, "pathPrefixFromAnnotation");
        return concatPaths(pathPrefix, pathPrefixFromAnnotation);
    }
Returns the path prefix to use. If there is {@link PathPrefix} annotation on the class
then path prefix is computed by concatenating pathPrefix and value from annotation else
returns pathPrefix.
core/src/main/java/com/linecorp/armeria/internal/server/annotation/AnnotatedServiceFactory.java