*   <li>Live: valid key/value are set
 *   <li>Loading: loading is pending
 * </ul>
 *
 * <p>Invalid:
 *
 * <ul>
 *   <li>Expired: time expired (key/value may still be set)
 *   <li>Collected: key/value was partially collected, but not yet cleaned up
 *   <li>Unset: marked as unset, awaiting cleanup or reuse
 * </ul>
 */
@GwtIncompatible
@J2ktIncompatible
interface ReferenceEntry<K, V> {

 *   <li>Live: valid key/value are set
 *   <li>Loading: loading is pending
 * </ul>
 *
 * <p>Invalid:
 *
 * <ul>
 *   <li>Expired: time expired (key/value may still be set)
 *   <li>Collected: key/value was partially collected, but not yet cleaned up
 *   <li>Unset: marked as unset, awaiting cleanup or reuse
 * </ul>
 */
@GwtIncompatible
@J2ktIncompatible
interface ReferenceEntry<K, V> {

    /**
     * Returns {@code true} if the value has been partially collected, meaning that the value is
     * null.
     */
    static <K, V, E extends InternalEntry<K, V, E>> boolean isCollected(E entry) {
      return entry.getValue() == null;
    }

    /**
     * Gets the value from an entry. Returns {@code null} if the entry is invalid or
     * partially-collected.
     */

## Partial updates with `PATCH` { #partial-updates-with-patch }

You can also use the [HTTP `PATCH`](https://developer.mozilla.org/en-US/docs/Web/HTTP/Methods/PATCH) operation to *partially* update data.

This means that you can send only the data that you want to update, leaving the rest intact.

/// note

`PATCH` is less commonly used and known than `PUT`.

    /**
     * Returns {@code true} if the value has been partially collected, meaning that the value is
     * null.
     */
    static <K, V, E extends InternalEntry<K, V, E>> boolean isCollected(E entry) {
      return entry.getValue() == null;
    }

    /**
     * Gets the value from an entry. Returns {@code null} if the entry is invalid or
     * partially-collected.
     */

        String result = facetInfo.toString();
        assertEquals("FacetInfo [field=[], query=[], size=null, minDocCount=null, sort=null, missing=null]", result);
    }

    // Test toString method with partially populated fields
    @Test
    public void test_toString_partiallyPopulated() {
        facetInfo.field = new String[] { "field1" };
        facetInfo.size = 20;
        facetInfo.sort = "term.asc";

  }

  /**
   * Catches a bug where when constructing a service manager failed, later interactions with the
   * service could cause IllegalStateExceptions inside the partially constructed ServiceManager.
   * This ISE wouldn't actually bubble up but would get logged by ExecutionQueue. This obfuscated
   * the original error (which was not constructing ServiceManager correctly).
   */

  }

  /**
   * Catches a bug where when constructing a service manager failed, later interactions with the
   * service could cause IllegalStateExceptions inside the partially constructed ServiceManager.
   * This ISE wouldn't actually bubble up but would get logged by ExecutionQueue. This obfuscated
   * the original error (which was not constructing ServiceManager correctly).
   */

   * be made {@code static} and its instances can be safely constructed and added in the {@link
   * ServiceManager} constructor without having to close over the partially constructed {@link
   * ServiceManager} instance (i.e. avoid leaking a pointer to {@code this}).
   */
  private final ServiceManagerState state;

  private final ImmutableList<Service> services;

  /**

    return new Segment<>(this, initialCapacity, maxSegmentWeight, statsCounter);
  }

  /**
   * Gets the value from an entry. Returns null if the entry is invalid, partially-collected,
   * loading, or expired. Unlike {@link Segment#getLiveValue} this method does not attempt to clean
   * up stale entries. As such it should only be called outside a segment context, such as during
   * iteration.