import java.util.Map;
import java.util.Set;

/**
 * Formatter that outputs index documents as JSON files.
 */
public class JsonIndexExportFormatter implements IndexExportFormatter {

    /**
     * Creates a new JsonIndexExportFormatter instance.
     */
    public JsonIndexExportFormatter() {
        // default constructor
    }

    @Override
    public String getFileExtension() {
        return ".json";
    }

        source.put("field_with_null", null);

        final String json = new JsonIndexExportFormatter().format(source, Collections.emptySet());

        assertFalse(json.contains("field_with_null"));
    }

    @Test
    public void test_jsonFormatter_emptyMap() {
        final String json = new JsonIndexExportFormatter().format(Collections.emptyMap(), Collections.emptySet());

        assertTrue(json.contains("{"));

        }
        switch (format.trim().toLowerCase()) {
        case "html":
            return new HtmlIndexExportFormatter();
        case "json":
            return new JsonIndexExportFormatter();
        default:
            throw new IllegalArgumentException("Unsupported export format: " + format);
        }
    }

    /**