doc: Add missing optional to MempoolEntryDescription

Author: MarcoFalke

src/rpc/blockchain.cpp

@@ -464,16 +464,23 @@ static RPCHelpMan getdifficulty()
 static std::vector<RPCResult> MempoolEntryDescription() { return {
     RPCResult{RPCResult::Type::NUM, "vsize", "virtual transaction size as defined in BIP 141. This is different from actual serialized size for witness transactions as witness data is discounted."},
     RPCResult{RPCResult::Type::NUM, "weight", "transaction weight as defined in BIP 141."},
-    RPCResult{RPCResult::Type::STR_AMOUNT, "fee", "transaction fee, denominated in " + CURRENCY_UNIT + " (DEPRECATED, returned only if config option -deprecatedrpc=fees is passed)"},
-    RPCResult{RPCResult::Type::STR_AMOUNT, "modifiedfee", "transaction fee with fee deltas used for mining priority, denominated in " + CURRENCY_UNIT + " (DEPRECATED, returned only if config option -deprecatedrpc=fees is passed)"},
+    RPCResult{RPCResult::Type::STR_AMOUNT, "fee", /*optional=*/true,
+              "transaction fee, denominated in " + CURRENCY_UNIT + " (DEPRECATED, returned only if config option -deprecatedrpc=fees is passed)"},
+    RPCResult{RPCResult::Type::STR_AMOUNT, "modifiedfee", /*optional=*/true,
+              "transaction fee with fee deltas used for mining priority, denominated in " + CURRENCY_UNIT +
+                  " (DEPRECATED, returned only if config option -deprecatedrpc=fees is passed)"},
     RPCResult{RPCResult::Type::NUM_TIME, "time", "local time transaction entered pool in seconds since 1 Jan 1970 GMT"},
     RPCResult{RPCResult::Type::NUM, "height", "block height when transaction entered pool"},
     RPCResult{RPCResult::Type::NUM, "descendantcount", "number of in-mempool descendant transactions (including this one)"},
     RPCResult{RPCResult::Type::NUM, "descendantsize", "virtual transaction size of in-mempool descendants (including this one)"},
-    RPCResult{RPCResult::Type::STR_AMOUNT, "descendantfees", "transaction fees of in-mempool descendants (including this one) with fee deltas used for mining priority, denominated in " + CURRENCY_ATOM + "s (DEPRECATED, returned only if config option -deprecatedrpc=fees is passed)"},
+    RPCResult{RPCResult::Type::STR_AMOUNT, "descendantfees", /*optional=*/true,
+              "transaction fees of in-mempool descendants (including this one) with fee deltas used for mining priority, denominated in " +
+                  CURRENCY_ATOM + "s (DEPRECATED, returned only if config option -deprecatedrpc=fees is passed)"},
     RPCResult{RPCResult::Type::NUM, "ancestorcount", "number of in-mempool ancestor transactions (including this one)"},
     RPCResult{RPCResult::Type::NUM, "ancestorsize", "virtual transaction size of in-mempool ancestors (including this one)"},
-    RPCResult{RPCResult::Type::STR_AMOUNT, "ancestorfees", "transaction fees of in-mempool ancestors (including this one) with fee deltas used for mining priority, denominated in " + CURRENCY_ATOM + "s (DEPRECATED, returned only if config option -deprecatedrpc=fees is passed)"},
+    RPCResult{RPCResult::Type::STR_AMOUNT, "ancestorfees", /*optional=*/true,
+              "transaction fees of in-mempool ancestors (including this one) with fee deltas used for mining priority, denominated in " +
+                  CURRENCY_ATOM + "s (DEPRECATED, returned only if config option -deprecatedrpc=fees is passed)"},
     RPCResult{RPCResult::Type::STR_HEX, "wtxid", "hash of serialized transaction, including witness data"},
     RPCResult{RPCResult::Type::OBJ, "fees", "",
         {