private Map<String, String> getConfigMapFromProperties(String prefix) {
        Map<String, String> rval = new HashMap<>();
        getKeys(prefix).forEach(pair -> {
            if (!pair.getKey().equals(prefix)) {
                String shortKey = pair.getKey().substring(prefix.length() + 1);
                rval.put(shortKey, pair.getValue());
            }
        });
        return rval;
    }
Gets all properties in the engine configuration that are prefixed
with the given prefix.
@param prefix the prefix
@return all prefixed properties
gateway/platforms/vertx3/vertx3/src/main/java/io/apiman/gateway/platforms/vertx3/common/config/VertxEngineConfig.java