static Set<String> keysWithVariableValues(Map<String, String> rawConfig, Pattern pattern) {
        Set<String> keys = new HashSet<>();
        for (Map.Entry<String, String> config : rawConfig.entrySet()) {
            if (config.getValue() != null) {
                Matcher matcher = pattern.matcher(config.getValue());
                if (matcher.find()) {
                    keys.add(config.getKey());
                }
            }
        }
        return keys;
    }
Checks a given {@link ConfigInfos} for validation error messages and adds an exception
to the given {@link Callback} if any were found.

@param configInfos configInfos to read Errors from
@param callback callback to add config error exception to
@return true if errors were found in the config
connect/runtime/src/main/java/org/apache/kafka/connect/runtime/AbstractHerder.java