Prevent arbitrary data transactions being created unless the network supports it (i.e. the hard fork has taken place).

src/main/java/org/qortal/arbitrary/ArbitraryDataTransactionBuilder.java

@@ -31,6 +31,9 @@ public class ArbitraryDataTransactionBuilder {
 
     private static final Logger LOGGER = LogManager.getLogger(ArbitraryDataTransactionBuilder.class);
 
+    // Min transaction version required
+    private static final int MIN_TRANSACTION_VERSION = 5;
+
     // Maximum number of PATCH layers allowed
     private static final int MAX_LAYERS = 10;
     // Maximum size difference (out of 1) allowed for PATCH transactions
@@ -132,6 +135,13 @@ public class ArbitraryDataTransactionBuilder {
     private void createTransaction() throws DataException {
         ArbitraryDataFile arbitraryDataFile = null;
         try (final Repository repository = RepositoryManager.getRepository()) {
+            Long now = NTP.getTime();
+
+            // Ensure that this chain supports transactions necessary for complex arbitrary data
+            int transactionVersion = Transaction.getVersionByTimestamp(now);
+            if (transactionVersion < MIN_TRANSACTION_VERSION) {
+                throw new DataException(String.format("Transaction version unsupported on this blockchain."));
+            }
 
             if (publicKey58 == null || path == null) {
                 throw new DataException("Missing public key or path");
@@ -172,7 +182,7 @@ public class ArbitraryDataTransactionBuilder {
                 throw new DataException("Unable to calculate file digest");
             }
 
-            final BaseTransactionData baseTransactionData = new BaseTransactionData(NTP.getTime(), Group.NO_GROUP,
+            final BaseTransactionData baseTransactionData = new BaseTransactionData(now, Group.NO_GROUP,
                     lastReference, creatorPublicKey, BlockChain.getInstance().getUnitFee(), null);
             final int size = (int) arbitraryDataFile.size();
             final int version = 5;