Review feedback from @gregtatcam

- Rewrite "Asset::native()" and "integral()" to use std::visit.
- Improve documentation for the LoanPay transaction flags:
  tfLoanFullPayment, tfLoanLatePayment

include/xrpl/protocol/Asset.h

@@ -81,13 +81,27 @@ public:
     bool
     native() const
     {
-        return holds<Issue>() && get<Issue>().native();
+        return std::visit(
+            [&]<ValidIssueType TIss>(TIss const& issue) {
+                if constexpr (std::is_same_v<TIss, Issue>)
+                    return issue.native();
+                if constexpr (std::is_same_v<TIss, MPTIssue>)
+                    return false;
+            },
+            issue_);
     }
 
     bool
     integral() const
     {
-        return !holds<Issue>() || get<Issue>().native();
+        return std::visit(
+            [&]<ValidIssueType TIss>(TIss const& issue) {
+                if constexpr (std::is_same_v<TIss, Issue>)
+                    return issue.native();
+                if constexpr (std::is_same_v<TIss, MPTIssue>)
+                    return true;
+            },
+            issue_);
     }
 
     friend constexpr bool

include/xrpl/protocol/TxFlags.h

@@ -272,8 +272,14 @@ constexpr std::uint32_t const tfBatchMask =
 // as an overpayment. False, no overpayments will be taken.
 constexpr std::uint32_t const tfLoanOverpayment = 0x00010000;
 // LoanPay exclusive flags:
-// tfLoanFullPayment: True, indicates that the payment is
+// tfLoanFullPayment: True, indicates that the payment is an early
+// full payment. It must pay the entire loan including close
+// interest and fees, or it will fail. False: Not a full payment.
 constexpr std::uint32_t const tfLoanFullPayment = 0x00020000;
+// tfLoanLatePayment: True, indicates that the payment is late,
+// and includes late iterest and fees. If the loan is not late,
+// it will fail. False: not a late payment. If the current payment
+// is overdue, the transaction will fail.
 constexpr std::uint32_t const tfLoanLatePayment = 0x00040000;
 constexpr std::uint32_t const tfLoanSetMask = ~(tfUniversal |
     tfLoanOverpayment);

include/xrpl/protocol/detail/ledger_entries.macro

@@ -572,7 +572,7 @@ LEDGER_ENTRY(ltLOAN, 0x0089, Loan, loan, ({
     //
     // - InterestOwedToVault = InterestOutstanding - ManagementFeeOutstanding
     //   The amount of the total interest that is owed to the vault, and
-    //   will be sent to as part of a payment.
+    //   will be sent to it as part of a payment.
     //
     // - TrueTotalLoanValue = PaymentRemaining * PeriodicPayment
     //   The unrounded true total value of the loan.