emptyGenerator = new EmptyGenerator();

        // Test adding conditions - this should work without container
        emptyGenerator.addCondition("field1", "pattern1");
        emptyGenerator.addCondition("field1", "pattern2");
        emptyGenerator.addCondition("field2", "pattern.*");

        // We can't test isTarget properly without container,
        // but we can verify conditions are added

        generator = new TestThumbnailGenerator();

        // Test adding single condition
        generator.addCondition("field1", "value1");

        // Test adding multiple conditions for same field
        generator.addCondition("field1", "value2");

        // Test adding conditions for different fields
        generator.addCondition("field2", "pattern.*");

        // Verify conditions can be added without errors

    }

    /**
     * Adds a condition for thumbnail generation.
     * @param key The condition key.
     * @param regex The regex pattern for the condition.
     */
    public void addCondition(final String key, final String regex) {
        final String value = conditionMap.get(key);
        if (StringUtil.isBlank(value)) {
            conditionMap.put(key, regex);
        } else {