*/
  @Synchronized
  @Throws(IOException::class)
  operator fun get(key: String): Snapshot? {
    initialize()

    checkNotClosed()
    validateKey(key)
    val entry = lruEntries[key] ?: return null
    val snapshot = entry.snapshot() ?: return null

    redundantOpCount++
    journalWriter!!
      .writeUtf8(READ)
      .writeByte(' '.code)

        jakarta.validation.Constraint constraint = CronExpression.class.getAnnotation(jakarta.validation.Constraint.class);
        assertNotNull(constraint);
        Class<?>[] validators = constraint.validatedBy();
        assertEquals(1, validators.length);
        assertEquals(CronExpressionValidator.class, validators[0]);
    }

    // Test validation with valid cron expressions
    public void test_validCronExpressions() {

        assertNotNull("Constraint annotation should be present", constraint);
        assertEquals("Validator class should be UriTypeValidator", UriTypeValidator.class, constraint.validatedBy()[0]);
        assertEquals("Should have exactly one validator", 1, constraint.validatedBy().length);
    }

    // Test default values
    public void test_defaultValues() throws Exception {

        assertNotNull("Constraint annotation should be present", constraint);
        assertEquals("Validator class should be CustomSizeValidator", CustomSizeValidator.class, constraint.validatedBy()[0]);
    }

    // Test default values
    public void test_defaultValues() throws Exception {
        final Field field = CustomSizeTest.class.getDeclaredField("testField");