public Map<String, Feature> readGroup(String groupName) {
if (groupName == null || groupName.isEmpty()) {
throw new IllegalArgumentException("groupName cannot be null nor empty");
}
if (!existGroup(groupName)) {
throw new GroupNotFoundException(groupName);
}
// Retrieve feature per feature (in-memory, no overhead)
Map<String, Feature> features = new HashMap<String, Feature>();
for (String feat : featureGroups.get(groupName)) {
features.put(feat, this.read(feat));