Address need not be optional when adding sapling keys

src/wallet/wallet.h

@@ -1058,11 +1058,11 @@ public:
     //! Adds Sapling spending key to the store, and saves it to disk
     bool AddSaplingZKey(
         const libzcash::SaplingExtendedSpendingKey &key,
-        const boost::optional<libzcash::SaplingPaymentAddress> &defaultAddr = boost::none);
+        const libzcash::SaplingPaymentAddress &defaultAddr);
     bool AddCryptedSaplingSpendingKey(
         const libzcash::SaplingFullViewingKey &fvk,
         const std::vector<unsigned char> &vchCryptedSecret,
-        const boost::optional<libzcash::SaplingPaymentAddress> &defaultAddr = boost::none);
+        const libzcash::SaplingPaymentAddress &defaultAddr);
 
     /** 
      * Increment the next transaction order id