refactor: Replace all uses of boost::optional with our own Optional type

After this:

- `boost::optional` is no longer used directly (only through `Optional`
    which is an alias for it)
- `boost/optional.hpp` is only included in one place

1 files changed, 2 insertions, 1 deletions

diff --git a/src/txmempool.h b/src/txmempool.h
index b51e800001..9ccede9d4d 100644
--- a/src/txmempool.h
+++ b/src/txmempool.h
@@ -17,6 +17,7 @@
 #include <coins.h>
 #include <crypto/siphash.h>
 #include <indirectmap.h>
+#include <optional.h>
 #include <policy/feerate.h>
 #include <primitives/transaction.h>
 #include <sync.h>
@@ -602,7 +603,7 @@ public:
     const CTransaction* GetConflictTx(const COutPoint& prevout) const EXCLUSIVE_LOCKS_REQUIRED(cs);
 
     /** Returns an iterator to the given hash, if found */
-    boost::optional<txiter> GetIter(const uint256& txid) const EXCLUSIVE_LOCKS_REQUIRED(cs);
+    Optional<txiter> GetIter(const uint256& txid) const EXCLUSIVE_LOCKS_REQUIRED(cs);
 
     /** Translate a set of hashes into a set of pool iterators to avoid repeated lookups */
     setEntries GetIterSet(const std::set<uint256>& hashes) const EXCLUSIVE_LOCKS_REQUIRED(cs);