*/
  @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)

/**
 * Validation constraint to ensure that a string is a valid cron expression.
 */
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER })
@Retention(RUNTIME)
@Documented
@Constraint(validatedBy = CronExpressionValidator.class)
public @interface CronExpression {

    /**
     * The error message when validation fails.
     * @return the error message
     */

 * This annotation validates URI strings based on specified protocol types.
 */
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER })
@Retention(RUNTIME)
@Documented
@Constraint(validatedBy = UriTypeValidator.class)
public @interface UriType {

    /**
     * Specifies the protocol type to validate against.
     *
     * @return the protocol type
     */
    ProtocolType protocolType();

/**
 * Validation constraint for custom size limits based on configuration keys.
 */
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER })
@Retention(RUNTIME)
@Documented
@Constraint(validatedBy = CustomSizeValidator.class)
public @interface CustomSize {

    /**
     * The error message when validation fails.
     * @return the error message
     */