jadler-core/src/main/java/net/jadler/KeyValues.java
public List<String> getValues(final String key) {
        Validate.notEmpty(key, "name cannot be empty");
        
        @SuppressWarnings("unchecked")
        final List<String> result = (List<String>) values.get(key.toLowerCase());
        return result == null || result.isEmpty() ? null : new ArrayList<String>(result);
    }
public List<String> getValues(final String key) {
        Validate.notEmpty(key, "name cannot be empty");
        
        @SuppressWarnings("unchecked")
        final List<String> result = (List<String>) values.get(key.toLowerCase());
        return result == null || result.isEmpty() ? null : new ArrayList<String>(result);
    }
Returns all values for the given key
@param key key (case insensitive)
@return all values of the given header or {@code null}, if there is no such a key in this instance