/**
     * Appends a key-value pair to the buffer in JSON format.
     *
     * @param buf the string buffer to append to
     * @param key the key name
     * @param supplier the value supplier
     * @return the updated buffer
     */
    protected StringBuilder append(final StringBuilder buf, final String key, final Supplier<Object> supplier) {
        final StringBuilder tempBuf = new StringBuilder();

    /** Unique identifier for the related query entry */
    @Required
    @Size(max = 1000)
    public String id;

    /** Username of the user who last updated this entry */
    @Size(max = 1000)
    public String updatedBy;

    /** Timestamp when this entry was last updated */
    @ValidateTypeFailure
    public Long updatedTime;

    /** Version number for optimistic locking */
    @Required
    @ValidateTypeFailure

	if r == nil {
		return nil
	}
	r.Lock()
	defer r.Unlock()
	// Search of tag key already exists in tags
	var updated bool
	for _, tag := range r.tags {
		if tag.Key == key {
			tag.Val = val
			updated = true
			break
		}
	}
	if !updated {
		// Append to the end of tags list
		r.tags = append(r.tags, KeyVal{key, val})
	}
	return r
}

        protected Writer writer;

        /** The stopword item being added or updated. */
        protected StopwordsItem item;

        /**
         * Constructs a new updater for a stopword item.
         *
         * @param newItem The item to be added or updated.
         * @throws DictionaryException if the temporary file cannot be created.
         */

		t.Fatalf("failed to query product, got error %v", err)
	}

	if result.Name != "Product 1 (Updated)" {
		t.Errorf("expected name to be 'Product 1 (Updated)', got %s", result.Name)
	}

	if result.Data != nil {
		t.Errorf("expected Data to be nil, got %v", result.Data)
	}

	// Test with non-nil value
	dataValue := map[string]interface{}{"key": "value"}

import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.concurrent.atomic.AtomicLong;

/**
 * A {@code double} value that may be updated atomically. See the {@link
 * java.util.concurrent.atomic} package specification for description of the properties of atomic
 * variables. An {@code AtomicDouble} is used in applications such as atomic accumulation, and

    @Required
    @Size(max = 1000)
    public String id;

    /**
     * The username of the user who last updated this role.
     * Used for audit trail purposes to track who made changes.
     */
    @Size(max = 1000)
    public String updatedBy;

    /**
     * The timestamp when this role was last updated.
     * Stored as a long value representing milliseconds since epoch.
     * Used for audit trail and concurrency control.

    @Required
    @Size(max = 1000)
    public String id;

    /**
     * The username of the user who last updated this label type.
     * Used for audit trail purposes to track who made changes.
     */
    @Size(max = 1000)
    public String updatedBy;

    /**
     * The timestamp when this label type was last updated.
     * Stored as a long value representing milliseconds since epoch.

        protected Writer writer;

        /** The stemmer override item being added or updated. */
        protected StemmerOverrideItem item;

        /**
         * Constructs a new updater for a stemmer override item.
         *
         * @param newItem The item to be added or updated.
         * @throws DictionaryException if the temporary file cannot be created.
         */

        existingSource.put(FieldNames.TAGS, Arrays.asList("existing"));

        Map<String, Object> updated = item.getUpdatedSource(existingSource);

        assertNotNull(updated);
        assertEquals("test", updated.get(FieldNames.TEXT));
        assertEquals(25L, updated.get(FieldNames.QUERY_FREQ)); // 20 + 5
        assertEquals(20L, updated.get(FieldNames.DOC_FREQ)); // 10 + 10

        @SuppressWarnings("unchecked")