Isso?

Validator.java

public class RulesProject {

    private static ResourceBundle projectFileList = ResourceBundle
            .getBundle("utfpr.edu.br.ex2.projectFileList");
    private static Map<String,String> propertiesMap = buildPropertiesMap(projectFileList);


    public static boolean validateFiles(Object bean, Field field) {
        return hasValue(ValidatorUtils.getValueAsString(bean, field.getProperty()));
	}

    /**
     * Create a specific Hash map of local ResourceBundle
     * used by default constructor to populate the properties file
     * @return 'Map<String,String>'
     */
    private static Map<String,String> buildPropertiesMap(ResourceBundle bundle){
        Map<String,String> propertiesMap = new HashMap<String, String>();
        //Get keys
        Set<String> keys = bundle.keySet();
        for(String key : keys){
            propertiesMap.put(key,getValue(key));
        }
        return propertiesMap;
    }

    /**
     * Get Property Value of
     * @param key
     * @return String value
     */
    private static String getValue(String key){
        return projectFileList.getString(key);
    }

    /**
     * Search for a '@param value' on properties file
     * @return Boolean result of search
     */
    private static boolean hasValue(String value){
        for (Map.Entry<String, String> stringStringEntry : propertiesMap.entrySet()) {
            Map.Entry pairs = (Map.Entry) stringStringEntry;
            if (pairs.getValue().equals(value)) return true;
        }
        return false;
    }