@Override
    public String toString() {
        return patternString();
    }
Invoked by {@link #apply(RoutingContext)} to perform the actual path matching and path parameter
extraction.

@param routingCtx a context to find the {@link HttpService}

@return a non-empty {@link RoutingResultBuilder} if the specified {@code path} matches this mapping.
        {@code null} otherwise.
core/src/main/java/com/linecorp/armeria/server/AbstractPathMapping.java