// Test getValues with non-existent key
        ExtractData data = new ExtractData();

        String[] values = data.getValues("nonexistent");
        assertNull(values);
    }

    public void test_getKeySet() {
        // Test getKeySet method
        ExtractData data = new ExtractData();

        data.putValue("key1", "value1");
        data.putValue("key2", "value2");
        data.putValue("key3", "value3");