*/
    protected void registerEnvItems(final RenderData data) {
        RenderDataUtil.register(data, "envItems", getEnvItems());
    }

    /**
     * Registers system properties for rendering.
     *
     * @param data the render data to populate
     */
    protected void registerPropItems(final RenderData data) {
        RenderDataUtil.register(data, "propItems", getPropItems());
    }

import org.lastaflute.web.response.render.RenderData;

public class RenderDataUtilTest extends UnitFessTestCase {

    public void test_register_null() {
        RenderData data = new RenderData();
        RenderDataUtil.register(data, "key1", null);
        assertNull(data.getDataMap().get("key1"));
    }

    public void test_register_string() {
        RenderData data = new RenderData();

import java.util.stream.Collectors;

import org.codelibs.core.beans.util.BeanUtil;
import org.dbflute.Entity;
import org.lastaflute.web.response.render.RenderData;

/**
 * Utility class for managing render data in web responses.
 * This class provides methods to register values in RenderData objects with proper handling
 * of Entity objects and Collections that may contain Entity objects.
 *
 */
public class RenderDataUtil {

    /**