// Test with empty document map
        Map<String, Object> docMap = new HashMap<>();
        assertFalse(thumbnailGenerator.isTarget(docMap));
    }

    @Test
    public void test_isTarget_withNullMimeType() {
        // Test with null mimetype value
        Map<String, Object> docMap = new HashMap<>();
        docMap.put("mimetype", null);
        assertFalse(thumbnailGenerator.isTarget(docMap));
    }