Eliminate special process logic for ManagedLedgerImpl

[BewareMyPower]

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Motivation

See https://github.com/apache/pulsar/pull/25016#discussion_r2560288325

Since https://github.com/apache/pulsar/pull/24622, when a managed ledger does not inherit ManagedLedgerImpl, the expiration check will use a different method, which is hard to test without a custom implementation.

        if (managedLedger instanceof ManagedLedgerImpl ml) {
            checkMessageExpiryWithSharedPosition(ml, messageTtlInSeconds);
        } else {
            // Fallback to the slower solution if managed ledger is not an instance of ManagedLedgerImpl: each
            // subscription find position and handle expiring itself.
            checkMessageExpiryWithoutSharedPosition(messageTtlInSeconds);
        }

However, in checkMessageExpiryWithSharedPosition, the only operation is getting the cursor with oldest position:

    private void checkMessageExpiryWithSharedPosition(ManagedLedgerImpl ml, int messageTtlInSeconds) {
        // Find the target position at one time, then expire all subscriptions and replicators.
        final var cursorWithOldestPosition = ml.getCursors().getCursorWithOldestPosition();

This should be a general operation that if the ManagedLedger#getCursors returns a correct cursor container, it should also work even if it's not a ManagedLedgerImpl.

Solution

No response

Alternatives

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Anything else?

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Are you willing to submit a PR?

• [ ] I'm willing to submit a PR!