builder.addEscape(' ', "-");
    builder.addEscape('!', "$");
    Escaper second = builder.build();
    // This should have no effect on existing escapers.
    builder.addEscape(' ', "*");

    // Test both escapers after modifying the builder.
    assertThat(first.escape("The Quick Brown Fox!")).isEqualTo("Xhe_Xuick_Xrown_XoxX");
    assertThat(second.escape("The Quick Brown Fox!")).isEqualTo("Xhe-Xuick-Xrown-Xox$");
  }

   * @throws NullPointerException if both {@code first} and {@code second} are null
   * @since 18.0 (since 3.0 as {@code Objects.firstNonNull()}).
   */
  public static <T> T firstNonNull(@Nullable T first, @Nullable T second) {
    if (first != null) {
      return first;
    }
    if (second != null) {
      return second;
    }
    throw new NullPointerException("Both parameters are null");
  }

  /**

  /*
   * Previously we had a field named set that was initialized to the value of
   * collection in setUp(), but that caused problems when a tester changed the
   * value of set or collection but not both.
   */
  protected final Set<E> getSet() {
    return (Set<E>) collection;
  }

                "Unknown q: " + query.getClass() + " => " + query);
    }

    /**
     * Converts a TermRangeQuery to a QueryBuilder with the given boost value.
     * Handles both search fields and default field queries with proper range semantics.
     *
     * @param context the query context
     * @param termRangeQuery the term range query to convert
     * @param boost the boost value to apply

        FessUserNotFoundException exception1 = new FessUserNotFoundException("user1");
        FessUserNotFoundException exception2 = new FessUserNotFoundException("user2");

        // Both instances should be of the same class
        assertEquals(exception1.getClass(), exception2.getClass());
    }

    public void test_stackTrace() {
        // Test that the exception has a proper stack trace

        FessUserTimeZoneProcessProvider provider2 = new FessUserTimeZoneProcessProvider();

        String result1 = provider1.toString();
        String result2 = provider2.toString();

        // Both should have the same format structure
        assertTrue(result1.startsWith("FessUserTimeZoneProcessProvider:{"));
        assertTrue(result2.startsWith("FessUserTimeZoneProcessProvider:{"));

        } catch (IllegalArgumentException e) {
            assertEquals("name or scriptEngine is null.", e.getMessage());
        }
    }

    // Test add method with both null parameters
    public void test_add_bothNull() {
        try {
            scriptEngineFactory.add(null, null);
            fail("Should throw IllegalArgumentException for null parameters");

  /**
   * Chooses and returns the representative instance for any of a collection of instances that are
   * equal to each other. If two {@linkplain Object#equals equal} inputs are given to this method,
   * both calls will return the same instance. That is, {@code intern(a).equals(a)} always holds,
   * and {@code intern(a) == intern(b)} if and only if {@code a.equals(b)}. Note that {@code

                                                    <td><fmt:formatDate value="${logFile.lastModified}"
                                                                        type="BOTH" dateStyle="MEDIUM"/></td>
                                                </tr>
                                            </c:forEach>
                                            </tbody>

 * limitations under the License.
 */

package com.google.common.graph;

import com.google.common.graph.GraphConstants.Presence;

/**
 * Standard implementation of {@link MutableGraph} that supports both directed and undirected
 * graphs. Instances of this class should be constructed with {@link GraphBuilder}.
 *
 * <p>Time complexities for mutation methods are all O(1) except for {@code removeNode(N node)},